Imp gear upgrade seems to delete your item in some cases?

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I'm not really sure about any other conditions to trigger this as this was the first time the imp has upgraded my gear, but I got the message saying my gloves were upgraded and when I checked my inventory they were gone. This was on the floor right before the plant boss, playing a warrior in singleplayer ng+0

[wispy sparrow]

I wonder if the bug lies with the item getting higher stat requirements when upgraded, kinda the game being unable to place the item back into your gear slot