I have a similar issue. When I try to replace a realm with a world on my Switch, the replacement fails with a nondescript error message. Also, when I try to play a pre-existing world on realms by creating a new realm, it loads a completely different world with no progress, not even the same seed. I now have three useless realms because of this issue.
I have a similar issue. When I try to replace a realm with a world on my Switch, the replacement fails with a nondescript error message. Also, when I try to play a pre-existing world on realms by creating a new realm, it loads a completely different world with no progress, not even the same seed. I now have three useless realms because of this issue.