Unable to import / reset world

Hello,

A friend wanted to replace his world on his Realm, except that each time an error message appears: "Failed to load". The map weighs around 420MB, but even with a 6MB world it doesn't work. Resetting the Realm doesn't work either. However the export works, it is after that it blocks, I put the screenshots in attachments. We tried everything:

Uninstall / reinstall Minecraft

Restart Minecraft

Close and reopen the Realm

Remove members

Click on "Play on Realm" or directly in the Realm settings on "Replace world"

Disable the firewall / or antivirus

Sign out / reconnect to Microsoft account ...

So I tried to buy a Realm myself on my account, it's exactly the same: systematic error even when trying anything and everything. Apparently this bug dates from last year ... and is still present. A lot of bugs are present in Minecraft, it does not generally matter they are corrected quickly but here we are paying for it.

What can we do ? Thanks for your help.