Remember to check MS store for updates (Gaming Services and the Xbox app have been updated recently) and also check for Windows updates.
(Remember to temporarily rename your community folder)
After launching the sim, the mandatory update was 8.5GB.
Once the sim opens, I had approx 5GB of updates in content manager (but this will vary depending on your settings)
Exit the sim, rename your community folder back to normal, and start the sim again. Fingers crossed

