Having Kui nameplates extra on disables them completely as the extra module is bugged. Kui nameplates will work when disabling the extra features, however. This only occurred after updating recently.

Here is the report:
Date: 2019-01-07 19:17:11
ID: 1
Error occured in: Global
Count: 1
Message: ...face\AddOns\Kui_Nameplates_Extras\modules\leftie.lua line 57:
attempt to perform arithmetic on field 'text_vertical_offset' (a nil value)
Debug:
...face\AddOns\Kui_Nameplates_Extras\modules\leftie.lua:57: UpdateHealthText()
Kui_Nameplates_Core\hook.lua:65: func()
Kui_Nameplates\messages.lua:128: DispatchMessage()
Kui_Nameplates\nameplate.lua:73: OnShow()
Kui_Nameplates\nameplate.lua:67: OnUnitAdded()
Kui_Nameplates\addon.lua:80: ?()
Kui_Nameplates\addon.lua:126:
Kui_Nameplates\addon.lua:123
Locals:
f = KuiNamePlate1 {
LevelText = {
}
Highlight = {
}
UpdateMainBars = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:469
parent = NamePlate1 {
}
UpdateHealthText = defined @interface\AddOns\Kui_Nameplates_Extras\modules\leftie.lua:50
UpdateRaidIcon = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:1444
AbsorbBar = {
}
UpdateFrameGlow = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:879
bg = {
}
UpdateGuildText = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:821
NameText = {
}
IN_NAMEONLY = true
unit = "nameplate1"
UpdateNameOnlyGlowSize = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:2017
state =

{
}
NameOnlyGlow = {
}
RaidIcon = {
}
animated_bars = {
}
ShowCastBar = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:1060
UpdateStateIcon = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:1406
CastBar = {
}
Auras = {
}
ThreatBrackets = {
}
UpdateFrameSize = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:397
UpdateAuras = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:1552
UpdateAbsorbBar = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:547
UpdateCastbarSize = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:1205
HealthText = {
}
StateIcon = {
}
handler = {
}
GuildText = {
}
SpellIconSetWidth = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:1053
0 =
UpdateFrameGlowSize = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:927
SpellIcon = {
}
UpdateCastBar = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:1163
PowerBar = {
}
SpellName = {
}
HideCastBar = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:1101
UpdateSpellNamePosition = defined @interface\AddOns\Kui_Nameplates_Extras\modules\leftie.lua:63
UpdatePowerBar = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:501
SpellShield = {
}
UpdateNameTextPosition = defined @interface\AddOns\Kui_Nameplates_Extras\modules\leftie.lua:32
elements = {
}
UpdateStateIconSize = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:1427
UpdateThreatBrackets = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:1910
UpdateHighlight = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:432
UpdateLevelText = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:729
CastBarUpdateFrame = {
}
BossModAuraFrame = {
}
HealthBar = {
}
UpdateNameText = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:679
ThreatGlow = {
}
cast_state = {
}
}
(*temporary) = nil
(*temporary) = -2
(*temporary) = true
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = "attempt to perform arithmetic on field 'text_vertical_offset' (a nil value)"
orig_UpdateHealthText = defined @interface\AddOns\Kui_Nameplates_Core\create.lua:779
mod = {
__EVENTS = {
}
Leftie_PostCreate = defined @interface\AddOns\Kui_Nameplates_Extras\modules\leftie.lua:82
Leftie_Init = defined @interface\AddOns\Kui_Nameplates_Extras\modules\leftie.lua:107
priority = 101
CustomCode_Init = defined @interface\AddOns\Kui_Nameplates_Extras\modules\custom.lua:5
enable_on_load = true
enabled = true
profile = {
}
config = {
}
Create = defined @interface\AddOns\Kui_Nameplates_Extras\main.lua:14
ADDON_LOADED = defined @interface\AddOns\Kui_Nameplates_Extras\main.lua:21
plugin = true
Leftie_PostShow = defined @interface\AddOns\Kui
AddOns:
Swatter, v8.0.6162 (SwimmingSeadragon)
Ace3, v
AucAdvanced, v8.0.6122 (SwimmingSeadragon)
AucFilterBasic, v8.0.6149 (SwimmingSeadragon)
AucStatHistogram, v8.0.6151 (SwimmingSeadragon)
AucStatiLevel, v8.0.6155 (SwimmingSeadragon)
AucStatPurchased, v8.0.6152 (SwimmingSeadragon)
AucStatSimple, v8.0.6153 (SwimmingSeadragon)
AucStatStdDev, v8.0.6154 (SwimmingSeadragon)
AucUtilFixAH, v8.0.6156 (SwimmingSeadragon)
BeanCounter, v8.0.6157 (SwimmingSeadragon)
BelowAverageItems, v1.29
ChatSounds, vv1.2.2
ClassicUI, v1.1.2
Clique, vv80000-1.0.0
CollectMe, v2.10.1
CrossRP, v1.8.0
DBMCore, v8.1.1
DBMDefaultSkin, v
DBMInterrupts, v7.3.0
DBMLDB, v
DBMStatusBarTimers, v
DejaCharacterStats, v800r103
Details, v
DetailsDeathGraphs, v
DetailsDmgRank, v
DetailsDpsTuning, v
DetailsEncounterDetails, v
DetailsRaidCheck, v
DetailsStreamer, v
DetailsTimeAttack, v
DetailsTimeLine, v
DetailsTinyThreat, v
DetailsVanguard, v
Elephant, v3.7.7
EmoteSplitter, v1.5.8
GatherMate2, v1.43.4
GnomTEC, v8.1.0.13
GnomTECNPCEmote, v8.1.0.22
HandyNotes, vv1.5.3
HandyNotesArgus, v0.20.0
HandyNotesBattleForAzerothTreasures, v1
HandyNotesBoralusRP, v0.331
HandyNotesBrokenShore, vv1.30
HandyNotesDraenorTreasures, v1.21
HandyNotesDungeonLocations, v1.45
HandyNotesHallowsEnd, vv1.4.3
HandyNotesLegionClassOrderHalls, vv1.30
HandyNotesLegionInstanceWorldQuests, vv1.17
HandyNotesLegionRaresTreasures, v1.1
HandyNotesLegionTreasures, v1
HandyNotesLunarFestival, vv1.5
HandyNotesSummerFestival, vv1.5
HandyNotesSuramarShalAranTelemancy, vv1.20
HandyNotesSuramarTelemancy, v1
HandyNotesTimelessIsleRareElites, v2.32
HandyNotesWarfrontRares, v0.5.0
HandyNotesWitheredArmyTraining, v1
Informant, v8.0.6159 (SwimmingSeadragon)
KuiMedia, v
KuiNameplates, v
KuiNameplatesCore, v
KuiNameplatesExtras, v3
LeatrixPlus, v8.1.00
Listener, v2.1.5
LucidNightmareHelper, v
MageNuggets, v6.1.1
MageNuggetsCooldownMonitor, v6.0.2
Misspelled, v1.7.2
npcGenerator, v
npcGToTRP3, v
NPCScan, v8.0.1.13
Pawn, v2.2.33
Postal, vv3.6.0
ProfessionAssistance, v3.5.6-HotFix
QuestCompletist, v109.20
SavedInstances, v8.0.8
SexyMap, vv8.0.8
Simulationcraft, v1.10.10
SlideBar, v8.0.6160 (SwimmingSeadragon)
SmexyMats, v8.1.0.2
Sounds4Chat, vv6.1.1
Stubby, v8.0.6161 (SwimmingSeadragon)
TomCats, v1.0.1
TomCatsDarkshoreRares, v1.2.5
TomTom, vv80001-1.0.2
totalRP3, v1.5.2
totalRP3Data, v
totalRP3Extended, v1.3.0
totalRP3ExtendedImpExport, v1.3.0
totalRP3ExtendedTools, v1.3.0
totalRP3KuiNameplates, v1.4.1
TransmogTokens, v1.4.9
WeakAuras, v2.10.11
WIM, v3.7.18
BlizRuntimeLib_enUS v8.1.0.80100
(ck=aae)