I managed to get 3 batches of these guys so I wanted to store them somewhere I wouldn't mistake them for new ones. when I tried using the lead on them nothing happens, even when shift clicking.
Linked issues
Comments 2
redstonehelper, technically they are alive due to them using the same entity of EntityHorse.
Also a duplicate of MC-75347.
Intended, you can't leash undead mobs. MC-44959.