@ArfurFarksache in my case I had restarted the sim after the issue with the plan screen, and it told me I had a mandatory update and told me to open the Windows Store app, so I opened that by clicking the start menu and typing “Store” into the search box, and then it said there was an update of about 1GB in size available for MSFS.
I downloaded that update, tried to start the sim again and then was met with the “Welcome, set your experience” screen which told me I had to download Sim Update 3 (which I’d already just downloaded).
I’m hoping it might work this time and resolve the issue but I’ll update the post either way. I’ve submitted a Zendesk report also.