Epic Solitaire Collection problem - excessive levelling up followed by "error: refer to...

Last Wednesday (4 May) on Solitaire Collection I earned a Golden Ticket, which enables me to earn double XP on every game I play for several days.

Earlier on today (6 May), I decided to see if I could achieve a double level up on a game of TriPeaks with endless boards and three deals. At this point, I was at level 286 of TriPeaks, and very close to level 287 - so I was looking to reach level 288 in this game. Being a Premium user, I was given the choice of a Wild Card or an extra deal before the game started - I decided that the extra deal would further boost my chances of achieving this double level up (along with the double XP granted by the Golden Ticket), so I took it.

Four deals later, I had completed 24 boards. 150 XP per board, doubled to 300 XP by the Golden Ticket - so I had earned 7,200 XP, which should have been enough to achieve this double level up. And it was.

But... after the level reached 288, it continued to increase. 289, 290, 291, 292, 293, 294...

I was shocked by what I was seeing - and not happily shocked. With the level still increasing (and past 300 by this point), I closed the Solitaire Collection app altogether.

When I opened the app again, I saw that the TriPeaks level had reached 319 - and I also saw the message "Xbox Live error: There was a problem saving your data to the cloud. Please check the Microsoft Solitaire Collection FAQ and refer to error code: 121010". And now I keep getting this message every time I close the app and open it again, and also every time I minimize the app and then maximize it again - and also after shutting down my laptop, leaving it for a few minutes, and then booting it up again.

I should point out three things here: (1) my laptop is a Dell Inspiron 13 7000 2-in-1 running Windows 10, (2) I have the most up-to-date version of Solitaire Collection (4.12.3171.0), as I allow my apps to be updated automatically, and (3) all my other apps continue to work normally.

So what has happened here? Has some kind of bug attacked? And can it be resolved without wiping all my (normal) Solitaire Collection stats and achievements - which include completing every Daily Challenge since June 2019, and earning at least one of every kind of bracelet in Events except the Spider Expert Dash bracelet (including five 1st Place Finish bracelets and over 100 Perfect Event bracelets)?

Thanks in advance.

:)