Wandering traders become invisible at night or when hostile mobs are nearby

I don't why, but it's really strange

 

Everytime I spawn a wandering trader and quit the world, they sometimes disappear when I enter the world again (even it's not midnight)

 

Even natural spawned mobs, tamed horse, pets (not sure yet) and other mobs disappear forever

 

I still don't know what's the cause of this bug but I hope this problem will be fixed soon