Steps to Reproduce:

1. Have no bones in your inventory
2. Kill a skeleton that drops bones
3. Walk over the bones so that they go into your inventory
4. Check your inventory and see if there are now bones in your inventory
5. If there are no bones, check if there is an empty slot in your inventory
6. If there is an empty slot, try to move something else into that empty slot

Observed Results:

When I pick up bones, they go into my inventory and then turn invisible. That spot in my inventory is then unusable. Items can't be placed in it and the bones cannot be moved out of that inventory slot.

Expected Results:

When I pick up bones, they appear in a slot in my inventory and can be moved around to other slots in my inventory.

I have attached a video of me attempting to shift click some rotten flesh into the first slot in my hotbar. It doesn't move into that slot because that position is filled up by bones that appear invisible.