Realm usually have error when you upload, download and replace your world.Try to do it in other devices until it work as my friends always do the same.
Everytime i update my server, i always copy :
server.properties
worlds (folder)
permission
whitelist (if you use it)
from the old server folder to the new server folder and run it.
Can you try again?
Don't use any 3rd party packs in your setting and try again.
Realm usually have error when you upload, download and replace your world.
Try to do it in other devices until it work as my friends always do the same.