1: I pick up a few bulky bits of loot, leaving no inventory room for my shield. Thank you, Recover Trap...
2: Before I think to organise it, i swap weapons and my shield auto-drops on the floor.
3; I pick it up and re equip it. It behaves normally.
4: 2 minutes later, if disappears off my PC's arm and vanishes out my inventory, leaving no log in the inventory.
I have now lost two +1 large shields to this bug and am considering moving to a small shield in part to slightly reduce the chances of this happening XD