I've been playing on my friends realm. I went afk at a mob grinder I recently made, but the trident killers werent working, and I had a load of mobs and a laggy mess to deal with.
I decided to move away from the farm to despawn them, And I came back 5 minutes later to find that no mobs have despawned. And I had to clear them out myself. :/
Comments 4
I think it was a spawner because it takes much longer and is much worse to make a mob grinder just by natural spawning
This is fixed in 1.16, see MCPE-66928.
Did this farm use a spawner? Mobs spawned by spawners do not despawn.
If the farm did not use a spawner, was the area where monsters collect lit? Monsters require light to despawn in Bedrock.
There are further conditions describe in the wiki. It is not clear from your report if your monsters met all of those conditions.