In Ninjago east side of the island, fighting a fire bear and he just despawns in the middle of battle. It also happened to transition to night time in that same moment.
Playing on PC.
#Bear despawned mid-fite because bedtime
fervent jay
fervent jay
Similarly, was battling another mob as it transitioned to day, mob despawned.
sour storm
I think this is intentional but an interesting choice on their part
strong jetty
Yeah it's not a bug. It's intentional. That's always been a feature. Though some mobs behave a little differently on the ninjago island than the rest of the world. I still think it's intentional.