Robbie R

Are you certain that your friend didn't Hide it somewhere? Their ender chest, or just a random container somewhere.

Also, how about building an iron farm. If there is an issue with smelting that'll skip it.

Tbh, I think that's just the way that seed generates. Cool find though.

Are you sure that in the case of the one with the chest, the items didn't just despawn?

I've been experiencing a similar issue. I play on Win10. Restarting the game nearly always fixes it.