How did you update the game? You can press escape to get back to the main menu on the campaign world.
Now i didn't lose any progress as i only completed 2 levels and i do have all dlc installed.
Did you use offline installers or gog galaxy to update?
Also i do know that the save files are in the documents on pc win 10.
I reinstalled the whole game when the new version came out since i am a little confused with the dlc.
Think you have to install 1.8p version of main game and then the 1.8p dlc versions.
Don't think you can just install the update when the previous versions of dlc are on it
I can run the levels though since i didn't get far.
Also used offline installers.
Anyway a side question how much do you like the game?
GOG automatically updated the game. Pressing escape from the campaign menu doesn't work. I also can't click on any of the levels. The ability for multiplayer/co-op is really the clincher there.
I like the game pretty well. Only bummer that I discovered after playing for a bit is that apparently the majority of the mods are only available through Steam workshop. So I partially regret buying it on GOG.