Originally, I attempted to bring a Realm backup down to my local PC and trim the nether and end by removing the DIM and DIM-1 folders.  I then added some Vanilla tweaks datapacks to the world (it already had some).  Finally, I uploaded it back to my realm.  Every time I logged out and back into the game, it would revert back to an earlier point in time and eliminate the progress I had achieved.  Assuming that the upload was bad, I restored a serverside backup from Tuesday (1.16 launch day), and abandoned my attempt to trim the nether/end.  That restoration took and I logged into the realm.  Again, there are instances where I log out and back in and the progress I have made has disappeared.  I move myself from one place to the other and log out.   I wait 3 hours and then log back in and I'm back at the original place.