I tried using the lead on a freshly spawned skeleton horse only to figure out that it would either mount me or open the inventory when crouched. I also tried to use it on a fence and that also failed.
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[MOD] Greymagic27
violine1101
I think we have another ticket for this that has been resolved as WAI. Though I haven't found it again yet.
Irbis
https://bugs.mojang.com/browse/MC-75347
@violine1101
migrated
Confirmed for 1.15 pre1