Not exactly a small or insignificant issue. Easy to reproduce or replicate. Simply enter a room (example: bunker) and stand against the wall. Go into inventory view (where you can see other items in the vicinity) and select an item to acquire. Move said item (example: backpack) into existing backpack slot, and current item (in this example: backpack) disappears (likely into the wall) along with all of its contents.

This also occurs with items you may acquire in the same manner when standing in a doorway, except in this case the item you were carrying goes into the floor partially beneath the threshold to where you can still see it but not access it.

How?!?

See above.

Obvious.