Microsoft Sudoku has once again lost my progress on daily challenges. Please advise when this issue will be fixed and my progress will be restored.

Looks like its fixed for me...
Hope its the same for all of you guys !!

As of today everything seems to be fixed. Sudoku remembers my Sudoku level when I exit and re-enter the game. Plus, it now remembers if I have a game in progress and exit Sudoku. When I come back in, it remembers the in-progress game and restores it to where I was at the time. Glad that everything now seems to be working as intended.

I think I've found the answer as follows:

Having tried the proposed solutions as above, I went for a "last ditch, last chance" solution before ditching SuDoku for good.

So I deleted the SuDoku App AND .... having wiped the 'Identity Provider' folders referred to above, I also deleted XBox.

I then re-downloaded and installed MS SuDoku from the Microsoft Store.

I DID NOT and HAVE NOT reinstalled XBox.

And SuDoku is now working perfectly, and has been doing so for the past few days.

Since then, I have NEVER received any notifications that I am offline.

Seems to me that rather than the SuDoku App, the problem lies with XBox

Worked for me too!

Thank you, this worked!

I got back the game I was last playing before this problem occurred, finished it, and reached level 371.

I really would hate to have lost that.

Again, thank you!

Pleased to report that the 'get rid of XBox App' solution is still continuing to work, right to the end of the month!

Only problem now is having to sit through those seemingly endless regurgitations of half-minute ads for that painfully awful 'Roger This' and 'Roger That' App.
And as a result, sadly, probably drinking more coffees than are healthy!!!