Since the Nov.17th update, my game refused to save any campaign progress (won scenarios + medals) and every game restart would get me back to the game status before any progress was made.
Doing some investigation, I found that the Steam Cloud space allocated for this game was basically full with 220 bytes left (you can check this on steam clicking on game properties/updates). I went to check my online cloud files and found that the file “Player.nfs” would not update since Nov.17th. This was not the case for my friend who did not have this problem.
You can check your storage here: https://store.steampowered.com/account/remotestorage
I tried a bunch of things but what eventually worked was to free up some Steam Cloud space by deleting, from within the game, some savegame files corresponding to those on the cloud. Now the problem seems to be gone and my progress saves fine as the “player.nfp” file updates every time I play. I am not sure on whether this was a bug in the first place or something odd with my specific account, but I have seen a bunch of other people with the same problem.
Hopefully this helps someone!