When I load my world, every once in a while when I get into the world almost all of the mobs will be gone, and (I think) only mobs within my render distance got removed. Even the nametagged mobs disappeared.
So far this has happened twice, I didn't report it the first time because I thought it might have been a fluke, but then it happened again. If you're wondering, the dates were 12/3 and 12/24. So far, this has only happened to one of my worlds.
Some things that might have affected this: 1) My world is pretty large filewise and 2) These both happened after making a copy of the original world, but this didn't happen every time i made a copy. Also, both the original and the copy are affected once it happens.
I don't know if this is a bug or not but I put it here anyways cause it's really annoying
Related issues
Comments

Thank you for your report!
We're tracking this issue in MCPE-144208, so this ticket is being resolved and linked as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki
-- I am a bot. This action was performed automatically! The ticket was resolved by one of our moderators, and I left this message to give more information to you.