Was trying out the equip option for the first time since installing the mod. Lurker pouch was a nice thing to have. Went to open it though after equipping a green gem amulet and things went sideways. Basically now when attempting to use the pouch instead of opening its normal window it literally takes over my inventory. All my gear disappears and any items I had in the pouch now are in my main inventory. To make it worse I thought to unequip everything to try fixing it. No good, when pressing C now it shows a small circle and nothing else. I've attached a screenshot.

Currently playing this on multiplayer, I went ahead and made sure I was on the current version, that the old core mod was removed and that the server version was being used on the server. Same issue.

One thing I did notice is that if I log off the server then back on my items will return but if I try using the pouch or equipment the same issue appears.

Mods:
ActuallyAdditions-1.12.2-r135
AkashicTome-1.2-10
angelRingToBauble-1.12-0.3.1.50+d4e654e
AppleSkin-mc1.12-1.0.9
appliedenergistics2-rv6-alpha-2
Aroma1997Core-1.12.2-2.0.0.0.b150
Aroma1997s-Dimensional-World-1.12-1.3.0.0.b37
astralsorcery-1.12.2-1.9.3
AutoRegLib-1.3-17
badwithernocookiereloaded-1.12.2-2.12
Baubles-1.12-1.5.2
bdlib-1.14.3.12-mc1.12.2
bedpatch-2.2-1.12.2
BetterAdvancements-1.12.2-0.0.5.17
BetterBuildersWands-1.12-0.11.1.245+69d0d70
BetterWithEngineering-1.6
BetterWithMods-1.12-2.3.3
BiblioCraft[v2.4.5][MC1.12.2]
binnie-mods-1.12.2-2.5.0.165
BiomesOPlenty-1.12.2-7.0.1.2398-universal
blockcraftery-0.1.3
BloodArsenal-1.12.2-2.1.0-24
BloodMagic-1.12.2-2.3.1-99
bonsaitrees-1.0.5-b77
Bookshelf-1.12.2-2.3.544
Botania r1.10-354
BrandonsCore-1.12.2-2.4.3.168-universal
BuildingGadgets-1.5.1
careerbees-0.4.0
Chameleon-1.12-4.1.3
ChickenChunks-1.12.2-2.4.1.71-universal
Chisel-MC1.12.2-0.2.0.31
chiselsandbits-14.19
ClocheCall-1.1.1
CodeChickenLib-1.12.2-3.2.0.345-universal
CoFHCore-1.12.2-4.5.2.19-universal
CoFHWorld-1.12.2-1.2.0.5-universal
ColossalChests-1.12.2-1.6.11
comforts-1.12.2-1.1.2
CommonCapabilities-1.12-1.4.0
compactmachines3-1.12.2-3.0.12-b215
CompactSolars-1.12.2-5.0.17.340-universal
Controlling-3.0.6
CookingForBlockheads_1.12.2-6.3.26
CraftTweaker2-1.12-4.1.9
CTM-MC1.12-0.2.3.12
CustomMainMenu-MC1.12.2-2.0.8
CyclopsCore-1.12.2-0.11.8
DankNull-1.12-1.4.33
DarkUtils-1.12.2-1.8.211
deepresonance-1.12-1.7.0
DefaultOptions_1.12.2-9.2.7
diethopper-1.1
Draconic-Evolution-1.12.2-2.3.12.297-universal
DummyCoreUnofficial-2.4.112.3
ElecCore-1.12.2-1.8.434
ElevatorMod-1.12.2-1.3.6
elulib-0.1.12
embers-0.230
EnderCore-1.12.2-0.5.35
EnderIO-1.12.2-5.0.29
EnderStorage-1.12.2-2.4.2.126-universal
environmentaltech-1.12.2-2.0.10a
EvilCraft-1.12.2-0.10.61
Exchangers-1.12.2-2.7.2
ExpandedEquivalence-1.12.2-10a
ExtraBotany-r1.1-30
extrautils2-1.12-1.8.1
ExtremeReactors-1.12.2-0.4.5.48
FarmingForBlockheads_1.12.2-3.1.21
FastWorkbench-1.12.2-1.3.2
flatcoloredblocks-mc1.12-6.6
foamfix-0.9.9.1-1.12.2-anarchy
forestry_1.12.2-5.8.0.290
Forgelin-1.6.0
ForgeMultipart-1.12.2-2.4.2.58-universal
FTBLib-5.0.2.14
FTBUtilities-5.0.2.14
funky-locomotion-1.12.2-1.1.1
gendustry-1.6.5.8-mc1.12.2
generators-0.9.20.12-mc1.12.2
gravestone-1.10.1
Guide-API-1.12-2.1.7-62
HammerCore-1.12.2-2.0.0.1
iceandfire-1.5.2
iChunUtil-1.12.2-7.1.4
ImmersiveCables-1.12.2-1.3.1
ImmersiveEngineering-0.12-84
immersivepetroleum-1.12.2-1.1.9
immersivetech-1.12-1.3.10
ImprovedBackpacks-1.12.2-1.3.0.0
industrialcraft-2-2.8.73-ex112
industrialforegoing-1.12.2-1.10.7-204
IntegratedDynamics-1.12.2-0.11.11
IntegratedTunnels-1.12.2-1.5.5
IntegrationForegoing-1.12.2-1.7.3
inventorysorter-1.12.2-1.13.3+57
IronBackpacks-1.12.2-3.0.7-10
ironchest-1.12.2-7.0.40.824
JEHC-1.12.2-1.6.1.0
jei_1.12.2-4.11.0.206
jeibees-0.9.0.5-mc1.12.2
jeiintegration_1.12.2-1.5.1.36
journeymap-1.12.2-5.5.2
JurassiCraft-1.12.2-2.1.14
JustEnoughResources-1.12.2-0.8.6.28
llibrary-1.7.14-1.12.2
LLOverlayReloaded-1.1.4-mc1.12
lostcities-1.12-2.0.7
LunatriusCore-1.12.2-1.2.0.42-universal
MagicalPsi-1.3
MagicBees-1.12.2-3.1.9
Mantle-1.12-1.3.2.24
mcjtylib-1.12-3.0.3
MCMultiPart-2.5.1
meecreeps-1.12-1.2.1
Mercurius-1.12.2
minetogether-1.10.2-1.8.7
MobGrindingUtils-0.3.6
modnametooltip_1.12.2-1.10.0
modtweaker-4.0.12
Morph-1.12.2-7.1.2
Morpheus-1.12-3.3.2
Morph-o-Tool-1.2-16
MouseTweaks-2.8-mc1.12.1
MrTJPCore-1.12.2-2.1.2.34-universal
MTLib-3.0.4
mystcraft-1.12.2-0.13.6.00
NetherPortalFix_1.12.1-5.3.13
Networks+Manager-12.0.3
NoMoreRecipeConflict-0.11(1.12.2)
NotEnoughIDs-1.5.4.2
notenoughwands-1.12-1.7.0
OpenComputers-MC1.12.2-1.7.2.67
p455w0rdslib-1.12-2.0.29
Pam's HarvestCraft 1.12.2u
Placebo-1.12.2-1.3.4
PortalGun-1.12.2-7.0.2
practicallogistics2-1.12.2-3.0.4
prefab-1.3.0.24
ProjectE-1.12-PE1.3.1B
ProjectRed-1.12.2-4.9.0.86-Base
ProjectRed-1.12.2-4.9.0.86-compat
ProjectRed-1.12.2-4.9.0.86-fabrication
ProjectRed-1.12.2-4.9.0.86-integration
ProjectRed-1.12.2-4.9.0.86-lighting
ProjectRed-1.12.2-4.9.0.86-mechanical
ProjectRed-1.12.2-4.9.0.86-world
Psi-r1.1-59
QuickLeafDecay-MC1.12.1-1.2.4
randompatches-1.12.2-1.4.1.1
RandomThings-MC1.12.2-4.2.0
rangedpumps-0.5
realfilingcabinet-1.12.1-0.1.57
reauth-3.6.0
RebornCore-1.12.2-3.9.2.319-universal
RebornStorage-1.12.2-3.2.1.63
RedstoneArsenal-1.12.2-2.5.1.13-universal
RedstoneFlux-1.12-2.0.2.3-universal
refinedstorage-1.6.2
refinedstorageaddons-0.4.1
ResourceLoader-MC1.12.1-1.5.3
rftools-1.12-7.55
rftoolsctrl-1.12-1.9.0
rftoolsdim-1.12-5.60
rftoolspower-1.12-1.1.1
rftpwr_oc-0.2
roots-2-0.104
Schematica-1.12.2-1.8.0.169-universal
Schematics-1.12.2.8
SimplyJetpacks2-1.12.2-2.2.4.34
sonarcore-1.12.2-5.0.12
Soot-0.15
stg-1.12.2-1.2.3
StorageDrawers-1.12.2-5.3.6
StorageDrawersExtras-1.12-3.1.0
TConstruct-1.12.2-2.10.1.87
Tesla-1.12.2-1.0.63
tesla-core-lib-1.12.2-1.0.15
Thaumcraft-1.12.2-6.1.BETA19
ThaumicAdditions-1.12.2-3r
thaumicbases-3.1.255.2r-ForTC6B17
ThaumicEquivalence-1.12.2-1.0.5
ThaumicInventoryScanning_1.12.2-2.0.10
ThaumicJEI-1.12.2-1.4.0-14
thaumicperiphery-0.2.4
thaumictinkerer-1.12.2-5.0-51a5074
TheBetweenlands-3.3.11-universal
theoneprobe-1.12-1.4.23
ThermalCultivation-1.12.2-0.3.0.7-universal
ThermalDynamics-1.12.2-2.5.1.14-universal
ThermalExpansion-1.12.2-5.5.0.29-universal
ThermalFoundation-1.12.2-2.5.0.19-universal
ThermalInnovation-1.12.2-0.3.0.7-universal
TipTheScales-1.12.2-1.0.1
Toast Control-1.12.2-1.6.0
ToolBelt-1.12.0-1.7.1
topaddons-1.12.2-1.6.0
Translocators-1.12.2-2.5.0.70-universal
twilightforest-1.12.2-3.7.424-universal
UniDict-1.12.2-2.5b
valkyrielib-1.12.2-2.0.10b
WanionLib-1.12.2-1.5
Waystones_1.12.2-4.0.54
WirelessCraftingTerminal-1.12.2-3.9.64
worldedit-forge-mc1.12-6.1.8-dist
xnet-1.12-1.7.3
zerocore-1.12-0.1.2.1

That's a very bizarre problem. I've seen other people report something similar with other backpacks too so I suspect it's another mod causing this problem. So far I've never run into this issue, but I'll check the code again and see if I can find something that could cause this

Update
Kept messing and it seems that if I create another pouch I'm able to equip it and the first pouch, eventually will end up back in my inventory. Still not sure what is causing the issue though but at least I have a work around.

Thought I would add a update. It appears that no aspects are being recorded in the Herblore Book aswell. Tried multiple items, each one says their is nothing left to discover but each page is still blank. Also, holding shift if post to show the aspect associated with the item after discovering it but that isnt appearing as well. At this point I'm wondering if it has something to do with the dimension I'm in when attempting all this? I've updated mods to the latest and forge as well.

The issue also exists for any rings I try to equip. After equipping a ring some time later I will notice that the symbol next to the toolbar is gone and so is the effects. Its almost like somehow it loses the item (ring or pouch) and can only be retrieved by equipping and unequipping another item to take its place. So the items arent being lost or sent to $null but only retrieveable after using the system to equip another item to force the current one out of its location. ugh...

List of Mods after updating.
ActuallyAdditions-1.12.2-r135
AkashicTome-1.2-10
angelRingToBauble-1.12-0.3.1.50+d4e654e
AppleSkin-mc1.12-1.0.9
appliedenergistics2-rv6-alpha-2
Aroma1997Core-1.12.2-2.0.0.0.b150
Aroma1997s-Dimensional-World-1.12-1.3.0.0.b37
astralsorcery-1.12.2-1.9.3
AutoRegLib-1.3-17
badwithernocookiereloaded-1.12.2-2.12
Baubles-1.12-1.5.2
bdlib-1.14.3.12-mc1.12.2
bedpatch-2.2-1.12.2
BetterAdvancements-1.12.2-0.0.5.17
BetterBuildersWands-1.12-0.11.1.245+69d0d70
BetterWithEngineering-1.6
BetterWithMods-1.12-2.3.3
BiblioCraft[v2.4.5][MC1.12.2]
binnie-mods-1.12.2-2.5.0.165
BiomesOPlenty-1.12.2-7.0.1.2398-universal
blockcraftery-0.1.3
BloodArsenal-1.12.2-2.1.0-24
BloodMagic-1.12.2-2.3.1-99
bonsaitrees-1.0.5-b77
Bookshelf-1.12.2-2.3.544
Botania r1.10-354
BrandonsCore-1.12.2-2.4.3.168-universal
BuildingGadgets-1.5.1
careerbees-0.4.0
Chameleon-1.12-4.1.3
ChickenChunks-1.12.2-2.4.1.73-universal
Chisel-MC1.12.2-0.2.0.31
chiselsandbits-14.19
ClocheCall-1.1.1
CodeChickenCore-1.10.2-2.4.1.102-universal
CodeChickenLib-1.12.2-3.2.1.349-universal
CoFHCore-1.12.2-4.5.3.20-universal
CoFHWorld-1.12.2-1.2.0.5-universal
ColossalChests-1.12.2-1.6.11
comforts-1.12.2-1.1.2
CommonCapabilities-1.12-1.4.0
compactmachines3-1.12.2-3.0.12-b215
CompactSolars-1.12.2-5.0.17.340-universal
Controlling-3.0.6
CookingForBlockheads_1.12.2-6.3.26
CraftTweaker2-1.12-4.1.9
CTM-MC1.12-0.2.3.12
CustomMainMenu-MC1.12.2-2.0.8
CyclopsCore-1.12.2-0.11.8
DankNull-1.12-1.4.33
DarkUtils-1.12.2-1.8.211
deepresonance-1.12-1.7.0
DefaultOptions_1.12.2-9.2.7
diethopper-1.1
Draconic-Evolution-1.12.2-2.3.12.297-universal
DummyCoreUnofficial-2.4.112.3
ElecCore-1.12.2-1.8.434
ElevatorMod-1.12.2-1.3.6
elulib-0.1.12
embers-0.230
EnderCore-1.12.2-0.5.37
EnderIO-1.12.2-5.0.30
EnderStorage-1.12.2-2.4.5.135-universal
environmentaltech-1.12.2-2.0.10a
EvilCraft-1.12.2-0.10.61
Exchangers-1.12.2-2.7.2
ExpandedEquivalence-1.12.2-10a
ExtraBotany-r1.1-30
extrautils2-1.12-1.8.1
ExtremeReactors-1.12.2-0.4.5.48
FarmingForBlockheads_1.12.2-3.1.21
FastWorkbench-1.12.2-1.3.2
flatcoloredblocks-mc1.12-6.6
foamfix-0.9.9.1-1.12.2-anarchy
forestry_1.12.2-5.8.0.290
Forgelin-1.6.0
ForgeMultipart-1.12.2-2.5.0.69-universal
FTBLib-5.0.2.14
FTBUtilities-5.0.2.14
funky-locomotion-1.12.2-1.1.1
gendustry-1.6.5.8-mc1.12.2
generators-0.9.20.12-mc1.12.2
gravestone-1.10.1
Guide-API-1.12-2.1.7-62
HammerCore-1.12.2-2.0.1.2
iceandfire-1.5.2
iChunUtil-1.12.2-7.1.4
ImmersiveCables-1.12.2-1.3.1
ImmersiveEngineering-0.12-84
immersivepetroleum-1.12.2-1.1.9
immersivetech-1.12-1.3.10
ImprovedBackpacks-1.12.2-1.3.0.0
industrialcraft-2-2.8.73-ex112
industrialforegoing-1.12.2-1.10.7-204
IntegratedDynamics-1.12.2-0.11.11
IntegratedTunnels-1.12.2-1.5.5
IntegrationForegoing-1.12.2-1.7.3
inventorysorter-1.12.2-1.13.3+57
IronBackpacks-1.12.2-3.0.7-10
ironchest-1.12.2-7.0.40.824
JEHC-1.12.2-1.6.1.0
jei_1.12.2-4.11.0.206
jeibees-0.9.0.5-mc1.12.2
jeiintegration_1.12.2-1.5.1.36
journeymap-1.12.2-5.5.2
JurassiCraft-1.12.2-2.1.14
JustEnoughResources-1.12.2-0.8.6.28
llibrary-1.7.14-1.12.2
LLOverlayReloaded-1.1.4-mc1.12
lostcities-1.12-2.0.7
LunatriusCore-1.12.2-1.2.0.42-universal
MagicalPsi-1.3
MagicBees-1.12.2-3.1.9
Mantle-1.12-1.3.2.24
mcjtylib-1.12-3.0.3
MCMultiPart-2.5.1
meecreeps-1.12-1.2.1
Mercurius-1.12.2
minetogether-1.10.2-1.8.7
MobGrindingUtils-0.3.6
modnametooltip_1.12.2-1.10.0
modtweaker-4.0.12
Morph-1.12.2-7.1.2
Morpheus-1.12-3.3.2
Morph-o-Tool-1.2-16
MouseTweaks-2.8-mc1.12.1
MrTJPCore-1.12.2-2.1.2.34-universal
MTLib-3.0.4
mystcraft-1.12.2-0.13.6.00
NetherPortalFix_1.12.1-5.3.13
Networks+Manager-12.0.3
NoMoreRecipeConflict-0.11(1.12.2)
NotEnoughIDs-1.5.4.2
notenoughwands-1.12-1.7.0
OpenComputers-MC1.12.2-1.7.2.67
p455w0rdslib-1.12-2.0.29
Pam's HarvestCraft 1.12.2u
Placebo-1.12.2-1.3.4
PortalGun-1.12.2-7.0.2
practicallogistics2-1.12.2-3.0.4
prefab-1.3.0.24
ProjectE-1.12-PE1.3.1B
ProjectRed-1.12.2-4.9.0.86-Base
ProjectRed-1.12.2-4.9.0.86-compat
ProjectRed-1.12.2-4.9.0.86-fabrication
ProjectRed-1.12.2-4.9.0.86-integration
ProjectRed-1.12.2-4.9.0.86-lighting
ProjectRed-1.12.2-4.9.0.86-mechanical
ProjectRed-1.12.2-4.9.0.86-world
Psi-r1.1-59
QuickLeafDecay-MC1.12.1-1.2.4
randompatches-1.12.2-1.4.1.1
RandomThings-MC1.12.2-4.2.0
rangedpumps-0.5
realfilingcabinet-1.12.1-0.1.57
reauth-3.6.0
RebornCore-1.12.2-3.9.3.324-universal
RebornStorage-1.12.2-3.2.1.63
RedstoneArsenal-1.12.2-2.5.1.13-universal
RedstoneFlux-1.12-2.0.2.3-universal
refinedstorage-1.6.3
refinedstorageaddons-0.4.1
ResourceLoader-MC1.12.1-1.5.3
rftools-1.12-7.55
rftoolsctrl-1.12-1.9.0
rftoolsdim-1.12-5.60
rftoolspower-1.12-1.1.1
rftpwr_oc-0.2
roots-2-0.104
Schematica-1.12.2-1.8.0.169-universal
Schematics-1.12.2.8
SimplyJetpacks2-1.12.2-2.2.7.45
sonarcore-1.12.2-5.0.12
Soot-0.15
stackable-1.12.2-1.0.0
stg-1.12.2-1.2.3
StorageDrawers-1.12.2-5.3.6
StorageDrawersExtras-1.12-3.1.0
TConstruct-1.12.2-2.10.1.87
Tesla-1.12.2-1.0.63
tesla-core-lib-1.12.2-1.0.15
Thaumcraft-1.12.2-6.1.BETA19
ThaumicAdditions-1.12.2-3r
thaumicbases-3.1.255.2r-ForTC6B17
ThaumicEquivalence-1.12.2-1.0.5
ThaumicInventoryScanning_1.12.2-2.0.10
ThaumicJEI-1.12.2-1.4.0-14
thaumicperiphery-0.2.4
thaumictinkerer-1.12.2-5.0-51a5074
TheBetweenlands-3.3.11-universal
theoneprobe-1.12-1.4.23
ThermalCultivation-1.12.2-0.3.0.7-universal
ThermalDynamics-1.12.2-2.5.1.14-universal
ThermalExpansion-1.12.2-5.5.0.29-universal
ThermalFoundation-1.12.2-2.5.0.19-universal
ThermalInnovation-1.12.2-0.3.0.7-universal
TipTheScales-1.12.2-1.0.1
Toast Control-1.12.2-1.6.0
ToolBelt-1.12.0-1.7.1
topaddons-1.12.2-1.6.0
Translocators-1.12.2-2.5.1.77-universal
twilightforest-1.12.2-3.7.424-universal
UniDict-1.12.2-2.5b
valkyrielib-1.12.2-2.0.10b
WanionLib-1.12.2-1.5
Waystones_1.12.2-4.0.54
WirelessCraftingTerminal-1.12.2-3.9.64
worldedit-forge-mc1.12-6.1.8-dist
WR-CBE-1.12.2-2.3.1.29-universal
xnet-1.12-1.7.3
zerocore-1.12-0.1.2.1