Playing on Xbox EU, I tried to start the Morrowind questline with one of my Alts (already completed it with two of them). When I try to progress the main questline by entering 'Andrano Ancestral Tomb' I get booted back to the Main Splash screen with 'Unable to connect to game server'.
Tried this with my main character as well (who has already completed the entire questline) and sure enough it crashes straight back to the Start.
This essentially breaks the entire questline (and if I were a new player, the entire game as they're now railroaded into starting in Vvardenfall).
Now before somebody tries to pass the buck (as per usual), no, this isn't due to an 'Xbox Live Service Interruption' - it's working fine for all my other games and the game actually allows me to get to Vvardenfell in the first place (which it wouldn't let me do if it didn't recognise I owned the content). I can also enter other locations in Vvardenfell with my main character, so there's nothing wrong there.
Nor is it 'my console' - after several 'cache clears', I eventually found it does the same whether I use my Xbox One S or my Xbox One X (which use different storage, so I essentially have two copies).
It seems to have done this since the last patch (and incidentally, the game seems to randomly decide whether or not it wants to use HDR each time I've started it since the last patch as well)
Morrowind has always been flaky on Xbox, ever since launch (if I had a dollar for every time I ran up invisible stairs in the Palace of Vivec, got 're-instanced' without warning, had the sound drop out or just had the whole thing lock up and crash, I could have paid for somebody to fix the damned thing), but now rendering the DLC 80% unplayable is ridiculous.
And if the answer is 'uninstall and reinstall again', then I'd rather just uninstall and get my money back, because I'm not buggering around by downloading and installing 81GB all over again, thanks...