[2023] The game works perfectly until a certain date arrives.

From your description this can really only be a game bug I'm afraid, so we can't fix it here for you.

Make a new thread in Bug Reports and attach the problem save there. Then put it aside and try it again as you see new patches come down.

Sorry for that problem!  

jfreif said: There are multiple threads on the Bug Report forum detailing this exact problem. When can we expect a fix? I'm sure I'm not the only to be disappointed in shelling out for new DLC only to not be able to play?

I'm not involved in the QA or dev teams, I am sorry - just an external contractor. Hopefully there'll be an update or patch soon!