Name Tagged Mobs/Leaded Mons Despawn

Despite having some mobs named with Name Tags or on a lead, the mobs just randomly despawn despite having the space/environment set to their requirements (for some more specific mobs like the Axolotl). When a mob is on a lead and it despawns, you're left with the end of the lead and you can't reclaim it as it's visually there but it also despawns with the mobs.

This is a very annoying bug as each time I log in to my realm/worlds, i have worry about my prized mobs vanishing. I've lost 2 naturally generated Pink Sheep and 1 skeleton horse to this bug along with many other mobs, which my friends on my realm have also suffered from. Please fix this! Thank you!