After traveling into the Nether, we can play for a couple of minutes and then the Realms server disconnects all players and then rolls back to an previous time. 

I downloaded my Realm World to attempt to debug on my local system (Xbox), and upon traveling into the Nether, the game crashes immediately and rolls back. 

I cannot upload a video clip due to file size restrictions, but I can invite you to my Realm if you need a demonstration of this issue.

From what I see on Reddit, this is a pretty common problem that is occurring with this recent update.