Wandering trader spawns with 2 llamas holding them on lead.

If I right click on one of the llamas with a lead, it will attached to it, however the trader still holds the llama, so I can't pull it. That's OK.

When I right click again to detach the lead, the lead becomes invisible in my hand. When I place an other item to that slot, it suddenly becomes visible.

Steps to reproduce:

1. Find a trader with llamas (I dug a hole below him to stand still)
2. First day there is a visible lead on llamas, that trader holds, so you can't attach a lead to the llama
3. However the next day after sleeping, this lead disappear, so you can attach your lead to the llama
   
4. Detach the lead and it becomes invisible
   
5. Seeking in the inventory it's still invisible
   
6. However if I place another thing to that slot, it becomes visible again