(First post, hi everyone)

I have encountered a recurring bug or something with Witcher 3 in the last week or so. I considered posting this in the W3 section but thought it would be better here.

I keep getting a red box with a triangle and exclamation mark where the 'synced' button is, next to 'Play'. It gives me the error "Cloud Sync Failed. There was a problem while syncing your cloud saves' with a retry option which does nothing. At first I ignored it and carried on playing (the game will launch after trying to sync for a bit), but I then noticed that achievements I completed in-game did not unlock in GOG Galaxy. This is a bit poo as I've finished the game and am achievement-hunting.
I have searched everywhere but cannot see anything quite similar to this happening within the last year. I tried older fixes like verify / repair etc but that didn't help. I've made sure it is listed in the firewall.

I can fix it temporarily by completely uninstalling and re-installing the GOG client. It then imports all my added games again (steam etc) and everything works perfectly. Saves sync and achievements unlock. It generally works fine for a day or so, even after 'sleeping' the computer, but eventually it reverts back to my old red-box nemesis and I have to uninstall and re-install again. It's getting a bit tiresome.

Any idea as to what I'm doing wrong?

Thanks in advance!