Reporting the same issues others have said in this thread.
Edit: I've e-mailed support already. Fingers crossed something can be done!
- Had I known an account transfer feature would be possible eventually, I would not have started GWENT progress on my GOG account (which has several games already, and I'd much rather keep everything on one account, including Thronebreaker).
- I split my playtime about 45%/55% between the UWP version and the Xbox One version, yet I'm getting the same error others have when I request an account transfer, stating there is no UWP progress for my Microsoft account.
Edit: I've e-mailed support already. Fingers crossed something can be done!