Jan Wintermans

Confirmed for 20w20b - example seed: 

2469973750442905586 

Coordinates: -26/81/335

I've had the same thing for quite some versions now, even in 1.8.x. I don't see the cause, it happens quite randomly for me.

Oh. I'm sorry! I've been asking a lot of other Minecrafters and nooone knew of it. I didn't know this was a known glitch.