We asked Ubisoft for comment on November 14th, but hadn’t received a response as of this writing. The issue appeared to be ongoing as of the 15th.
It’s not certain how widespread the save game issue is. It’s a serious glitch for anyone affected, though — there’s not much incentive to play if you can’t guarantee that hours of progress will be there when you return. While this isn’t Ubisoft’s first experience with a flawed game launch, it may be a painful one when Valhalla and Legion are major launch titles for the PlayStation 5 and Xbox Series X.