Coop career stuck on "Saving to online services" loop

Me and my friend were running a coop career for a while now, we are on our second season. After a race in Austria, online connectivity broke between us (although it was probably not full internet outage since our connection on discord stayed, with everything else internet related). After this event i tried rejoining the session, we got to the race summary screen, but after that no luck, only a loop saying Saving to online services, then black screen, and back to loading again. Same can be said for my friend. Please help us resolve this, a lot of time went into this save file already :( We suspect it has to do something with save file syncing, it seems like there is a constant mismatch or something.... 

We are both playing through the Steam version on PC, our gametags:
A Family Friendly Polar Bear
JonklerMTA

JonklerMTA is the owner of the savefile, while I was the one who got invited to be the coop driver.