When you upload a world to realms it seems to overwrite the region file where the player is located to default terrain.
I had a 1.15 void world which i joined on 1.16 and it seemed to work fine but after it was uploaded to realms the region I was located it was converted to default terrain but only for about a few hundred block and then it was back to the void with my builds that diddnt get overwritten
Thank you for your report!
Minecraft Realms for Java Edition has received a lot of updates and fixes over the last two years, so this issue has probably already been fixed in the meantime (e.g. because it was a temporary outage or an issue with the base game).
Since this bug report has not been updated since at least two years, please let us know if this is still an issue in current versions of Minecraft and update the bug report if applicable. If this is no longer an issue, please let us know as well. Thanks!
This issue is being temporarily resolved as Awaiting Response. Once the requested information has been delivered, the report will be reopened automatically.
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