I initially reported this to the mod author of Draconic Evolution. I'm currently developing my own custom modpack and discovered that when attempting to equip my player with armor, or tools, from DE - while running Zyin's HUD, all items will immediately be removed and returned to an available inventory slot.

I'm currently running version 1.3.9 of ZyinsHUD for MC1.7.10 and was able to reproduce the error with the last two versions of DE available on that mods site. It seemed to only affect that mod, so I dropped the author an issue report, but thought I'd drop one here too, in the event someone else has come across a similar issue running ZyinsHUD.

@Zyin055 Hello Im the author or Draconic Evolution and im happy to help try to figure out what it is about my armor that causes this issue but i cant think of anything on my end that could cause this issue.

As a work around, I jumped into the configs and disabled the option to unequip armor and tools before they break and it appears that the DE items now remain where they were placed. Not sure if that is something to do with NBT data is handled by either mod, but thought I'd share my findings in case it helps narrow down the root cause.

@Zyin055 Looks like it its with the way my armor handles damage. Your mod thinks its about to break and moves it to the players inventory. Perhaps you could add a check for Item#getMaxDamage <= 0