Animals with nametags still despawn

Mobs with nametags still despawn. I have been playing my creative world recently. I had spawned a llama and named it. A few weeks later the llama had despawned even when it was named. Another situation had occurred in late 2020, I had spawned a bunch of untamed wolves and named them. I did not tame them. A few days later most of them were gone and there were only 10 left. Hoping this is fixed soon. The mobs couldnt have escaped because they were inside a fenced in area.