The bug
If an animal is put on a leash that is held by a player and not by a fence, the lead will completely disappear after logging out of the world and logging back in. It doesn't break and drop, it doesn't become invisible and it doesn't glitch out, it simply disappears totally like it was never existed.
To reproduce
Put an entity on a lead in a singleplayer world
Leave the world
Open the world again
→ ❌ The lead completely disappears
Videos
Related issues
is duplicated by
relates to
Attachments
Comments

This is the same issue as MC-14826: Leads become invisible when chunks are reloaded. If you want, you can add any further information that you found out to that ticket and give that ticket a vote.

— Leads become invisible when chunks are reloaded
If you with invisible mean that the lead isn't visible but it's still there holded by the player, then this isn't the case. In this case, logging out and logging back into world makes the lead disappear like it wasn't never used regardless, and this is bad because the lead used doesn't show up in the inventory anymore, meaning you just lost an item without a reason (and a rare one, since slime balls aren't so easy to find in a normal survival world). I even tried to reload the chunks with F3+A while holding an animal with a lead, and the lead was totally fine, but when I logged out and logged back, as expected, the lead disappeared, and it wasn't dropped or got back in the inventory. This problem isn't specifically mentioned in that thread, and I can show you another clip of this issue, if needed
Alright, then I misunderstood your issue. Reopened.

Okay, thanks

I was able to replicate the bug just in case me commenting helped in some way to getting the bug fixed.

The more the bug get noticed, the more are the chances of being fixed

I uploaded a new clip where I tried to replicate this bug in snapshot 13w16a, or the first version where leads were added. It partially works, becuase when I reload the world, the lead drops to the ground instead of disappearing, so I can assume that this bug exists since the introduction of leads in 13w16a, but only got worse at some point. I'll upload the affected version's list Edit: Nevermind, I can't add other versions affected apart from 1.14.4, future 1.15 and latest snapshot (19w36a)

Can this still be reproduced in 1.15-pre1?

— Can this still be reproduced in 1.15-pre1?
Yes, it can

Bug still present in release 1.15

I cannot reproduce 1.16.3
Can't reproduce either.