Manually syncing time didn't have any effect for me on my Win11 kit.
I fired up Windows Store this afternoon, headed to Apps and got all the pending updates. Lots of them, many with no particular relation to MSFS. I tend to do this just before an MSFS app update but thought I'd give it a go for this issue.
Thereafter all good! My hunch is that there was one or more interdependencies between some modules that had got out of step with each other.
Or maybe someone just fixed things server side. Who knows...anyhow happy to be back in the air ๐.