Having this issue too recently. Not sure if related, but I had also been using zombie villagers to infect other villagers, but recently the zombie villager will kill the villager instead of just infecting it
This has been happening to me as well. I will use a nametag to name captured zombies or zombie villagers, leave the area, come back and they'll be gone. I'm on a realm so I thought people were killing them, but they're just dissapearing.
I play Minecraft on my Google pixel 3a. When I attempt to upload a world to my realm it shows the export bar then says upload in progress but then nothing happens and then it says error.
Thank you for your response. I know the player is stuck in creative mode because they told they are. Yes they can fly around and have unlimited inventory. I've tried changing them to visitor/member/operator and nothing seems to work. I can take a look at using a world editor. If it all possible I would like to keep achievements on as this is my primary world I play in.