This issue blocks the items from being seen in the vicinity window and they must be picked up via looking at the item and pressing F.

The road flare and boxed 5.56 are two of the worst offenders of this issue in my experience, they very frequently get stuck in objects, both when spawning in the world naturally or when a player manually drops the item themselves.

I haven't tested this in every single building but I can say the issue happens relatively frequently in military buildings such as the barrack variants.