I have a realm (Windows 10 + Xbox users) and not only are our captured animals despawning, but even animals with nametags who have been interacted with many, many times!
We are getting so frustrated because sometimes horses with nametags applied, armour and saddles disappear completely from their stalls and we lose all the gear applied to them too.
I can't turn on coordinates without turning on cheats on our realms. 😞
However, we had tamed/saddled horses and blanketed llamas disappear both very close to our nether portals and almost a KM away too.
Our portal is somewhat close to spawn as well, if that's important.
And all our users have different render distances, I'm guessing.Â