Issue Description:

Backpack contents disappear completely.

I assembled this collection of of mods yesterday. Both today and yesterday it cleared contents on at least one occasion each.

What happens:

I put items in my backpack, and twice now I've observed that opening it some time later (same real-time day, probably several MC days, there might have been a server restart if it hung itself up, but no log entries about the hang, just have to ctrl-C it**--Edit: Nope, the next server restart due to hang didn't clear it--**), it's empty.

It's a simple first-tier leather-and-chest backpack. No upgrades or metals.

If it matters, I'm wearing the backpack. I bound the hotkey for this to V.
I bound (or left it default) the hotkey for checking the backpack to R. Coincidentally, this is also the inventory tweaks sort button, but they seem to work together just fine. I acknowledge this could be the issue; has this been noted and determined unfixable?

Iron Backpacks was a special request by my wife, so I'd love to figure out why or what is causing it to clear contents.

Steps to reproduce (important):

I haven't been able to identify the specific circumstances, but am hoping to solicit testing advice to narrow this down.

Is there a verbose logging option somewhere that could yield insight? Is there a logging action somewhere likely to say something to the effect of, "[backpack data corrupt; discarding]"

I'm tempted to write a watcher script to let me know when the backpack content file zeroes-out, but I haven't dived into the save-structure for Iron Backpacks enough to know what file it is, or whether that would be a practical approach (all backpacks in a save into one file? backpack as part of the character's NBT?)

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Affected Versions (Do not use "latest"):

• IronBackpacks: IronBackpacks-1.7.10-1.2.20.jar
• Minecraft: 1.7.10
• Forge: MinecraftForge v10.13.4.1614
• Other Conflicting Mods (may be irrelevant to your issue):
  appliedenergistics2-rv2-stable-10.jar
  BiblioCraft[v1.11.7][MC1.7.10].jar
  BiblioWoods[Forestry][v1.7].jar
  buildcraft-7.1.23.jar
  ChromatiCraft+1.7.10+V22d.jar
  CodeChickenCore-1.7.10-1.0.7.47-universal.jar
  DragonAPI+1.7.10+V22d.jar
  ElectriCraft+1.7.10+V22a.jar
  EnderStorage-1.7.10-1.4.7.37-universal.jar
  ExpandedRedstone+1.7.10+V22a.jar
  forestry_1.7.10-4.2.16.64.jar
  iChunUtil-4.2.3.jar
  IguanaTinkerTweaks-1.7.10-2.1.6.jar
  InventoryTweaks-1.59-dev-152.jar
  journeymap-1.7.10-5.1.4p2-unlimited.jar
  Mantle-1.7.10-0.3.2b.jar
  mystcraft-1.7.10-0.12.3.04.jar
  NotEnoughItems-1.7.10-1.0.5.120-universal.jar
  PortalGun-4.0.0-beta-6-fix-1.jar
  Railcraft_1.7.10-9.12.2.1.jar
  ReactorCraft+1.7.10+V22a.jar
  RotaryCraft+1.7.10+V22d.jar
  TConstruct-1.7.10-1.8.8.jar
  Thaumcraft-1.7.10-4.2.3.5.jar
  UndergroundBiomesConstructs-1.7.10-0.8-beta49.jar
  VillageNames-1.7.10-3.1.jar
  witchery-1.7.10-0.24.1.jar
  WitcheryPatch-1.7.10-1.0.0.jar

Crap, now I see that 1.7.10 is unsupported.

Any information on this, especially known issues, would be appreciated; I acknowledge no code is likely to be submitted to fix the issue. I just want 1.7.10 because two of my favorite mods which I haven't "completed" are 1.7.10 only.

The cause of the hangs-to-infinite, as revealed by Opis, was VillageNames. With that removed, I don't get the crashes, but I did still get an Iron Backpack (this time an Iron one, on my back) inventory clear.

I was delving in a Chromaticraft Cavern this time. I ran out of inventory space, so I put the contents of the loot chests and some gold ore blocks in my Iron Backpack. Then, not 2 minutes later, when I wanted to put some crystals and black stone from the walls of it in there, it was empty.

How can I learn the cause of the clearings?