I've noticed reports of something simillar happening on android and switch as well, with either the game failing the copy or full out crashing. Examples such as MCPE-40286 and MCPE-41568
I've had a simillar issue on my switch 😞
This was also not fixed in the 1.9 Update - World size of 282.1 mb no crash, World size of 2.89.3 crash.
I feel like I can't play minecraft safely without being able to back up, so haven't been able to play. An acknowledgement or advice from a mod would be nice but that's probably too late and this has fallen into oblivion
Did anything ever come of this?
According to the change log - this has been fixed as of 1.10. I can confirm it has worked for me