So last week I created a new survival world in the new 1.11.0.9 beta on my xbox one, and I've noticed that mobs and entities, specifically dropped items and xp orbs. I first noticed it when I went to my blaze farm and all the blazes (probably about 15 or 20) were still there! This was after I had went back to the overworld for many nights AND exited and saved multiple times. Since then, I've noticed that sometimes dropped items will last way past 5 minutes and past exit and saves. Xp orbs stay as well. I have killed mobs hundreds of blocks away from my house and even after many minecraft days have passed I can go back and collect the experience.
I'm pretty sure that this bug is affecting the spawning of hostile mobs on the surface as well because I try to go out at night to get ender pearls and I'll be lucky if I see even a single zombie! Please read this so I can go to the end!
Related issues
Comments

Thank you for your report!
We're actually already tracking this issue at MCPE-21856, so we will resolve and link this ticket 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.
Please note: Mob spawning in Bedrock is very different from in Java. You might want to see the wiki article on Spawning for some information on how spawning works in Bedrock. However, even in Java, entities (mobs and items) only despawn while there is a player in the same dimension, so returning from your blaze farm to the overworld would cause the blazes, dropped items, etc. to not despawn before you returned.