We play on a world, which suddenly becomes laggy and then kicks everyone. My friends on Xbox and Win 10 tried to get back on, but it showed up saying that the world is corrupted. When I (the owner) try to get back on, it would get stuck on the portal waiting screen (usually loading resource packs). I waited 20 mins without success, and decided to close Minecraft. 

Then I download the world. I open it in singleplayer mode and it shows up with the message that the world is corrupted. I go back to menu and open the world again. Works fine afterwards. 

If I try and replace the world now, it works, but when opening the realm it still doesn't let us on. After hours of failure, I closed and reopened the realm and reuploaded the world. It works now.

The worlds were all fine. However, after the recent 1.14 update, I updated as instructed. The same issue as above happened. However, this time when I opened the realm, after a minute or so of playing, it showed me the message that the world was corrupt mid-playing, and subsequently kicked me. After this, every time I try to enter the realm, it pops up with the message "Unable to Connect to World". Sometimes this happens after the "Loading Resource Packs..." goes away, but other times it jumps to it straight away. One other problem I faced, was that the downloaded world was a mixture of the original world (before we started playing) and of the current world. Please see attached picture. The bit on the left is a chunk of the current world, however, the other side (possibly another chunk) is the original. Most chunks have been reset. Aside from that, in the backups tab in the realms options, I downloaded the backup of a world 22 hours ago (when the world was normal). The downloaded world was in fact the world that has a mixture of old and new chunks. 

Luckily, I had a backup saved to my internal storage of a world 2 days prior to this. Otherwise, all our hard work would have been deleted (other than the few chunks that remain). 

I would greatly appreciate any help or updates.