when you lead an animal and put the lead on a fence, and when you die and respawn in the chunk that was loaded when you died the lead in the fence is invisible
how to reproduce
1 lead an animal at the spawn area
2 turn on cheats and do /kill (but you have to respawn in the same chunk the lead is in before you died 🙂 )
3 observe the invisible lead
Duplicate of MC-14826 - If you have not, please use the search function in the future, to see if your bug has already been submitted. If you could not find the original report, please comment with the keywords you searched for.