COOP savegames broken?

[Dartas]

Me and my mate are having an ongoing game with 50h+. Recently we have the problem that the save games are broken: Sometimes there is no COOP (highlighted in blue) in the save game and with that my mate cant join the game anymore. The only choice is reloading an old save file and having to redo everything of the last hours... Does anyone have a solution yet? Is this a known bug?

[Valerius]

This is actually a simple fix. Just go into Multiplayer and click "load single player game". The game opens a new lobby you can invite your steam-friend right away as long as he's online. Make sure you 100% have the same res.pak. This normally only happens when the game can't properly synch things. We've had this too.

Yet: The real issue starts when the game doesn't let you load the savegame at all anymore. https://steamcommunity.com/app/1527950/discussions/0/4631482745020770563/