After a hopper or hopper minecart sucks a bundle out of a container, the bundle becomes corrupted in a way that isn't immediately visible. If you then spill its contents on the ground, the contents are dropped but in your inventory the bundle still shows that it contains them. Nevertheless, they are ghost items: You can't take them out, nor can you put additional items of those types in (though you can put items of a new type in).

Note that you can restore correct operation of the bundle by putting the bundle with ghost items (and nothing else) back in the container and letting it be sucked again. This turns it into a normal empty bundle again.

Steps to reproduce:

1. Set up a chest or barrel above a hopper.
2. Acquire an empty bundle and a bunch of loose items to put into it.
3. In your inventory, click the bundle on the loose items (or vice versa) to put them in.
4. Place the bundle in the chest or barrel and remove it from the hopper.
5. Select the bundle in your hotbar and right click to spill its contents on the ground.
6. In your inventory, notice that the bundle still shows as containing the items.
7. Pick up the spilled items and try to put them in the bundle. Notice it doesn't work.
8. Place the bundle in the chest or barrel again and remove it from the hopper. Notice that it now shows as empty in inventory and again works correctly.

Expected results:
After passing through a hopper, a bundle works normally in all situations.

Observed results:
After a bundle passes through a hopper and you then spill its contents on the ground, a bundle acquires ghost items and no longer accepts or yields those items.