I just got back in! I was about to uninstall the whole game and reinstall it and stumbled across this info about moving the Packages outside of the overall game file to keep from having to reinstall all the content when all I want to do is uninstall the game. (I was considering dropping out of the SU4 beta to see if that would fix things.) Anyway, I followed these instructions to move the Packages to a new folder on my C:drive and when I restarted I was able to re-enter Career Mode (the mandatory Cessna message was gone).
Not sure if this will be a permanent fix, but it got me further than I’ve been.
I know its for 2020 but I was able to make it work for 2024. Hope this helps someone else.
Thanks