Thanks for the replies but so far there is no resolution.
I have only 1 campaign running in the game.
I tried the renaming of the folder several times. What happens is that in the game for a moment there are 2 campaigns. Often the 'old' name disappears again when going from one screen to the other. There is not any campaign with save games though. I tried restarts of the game / computer a few times.
One time I had 2 campaigns with about the same name. I deleted one and it seemed to be the one containing the save games on my hard disk. After that I copy-pasted my backup of those files in the campaign folder again of my windows system. Issue still persists.
Any further suggestions
-K K