Duplicating a Minecraft world crashes Minecraft.

To recreate the issue,

click :

*Play

*The pencil button next to the world

*Scroll down and click Duplicate world.

Minecraft duplicates the world successfully, then crashes.

So far all my backups work, but this is CERY unnerving! 

There's also a problem with the site when displayed on Microsoft Edge. The thing refuses to accept the keys tyi[aflm./  

It was impossible to search for the bug on windows. I'm using my phone to do this!