Oh darn, that's shot my Heinkel down,
Its beginning to sound as if it must be something external, perhaps a Windows 10 "feature" that is screwing things up. I freely admit I have been messing with screen settings since the eye operations started in September and some of those just wouldn't co-operate with FS at all. I didn't think I fiddled with these at the time of that update but to satisfy myself, I might make a new install and use an older manual update to bring it up to a relatively recent but not current version and see what happens then. I will de-register the existing version first, so hopefully I won't run out of "uses".
Looking back through my downloads of PF3_Cumulative_Updates_Setup.zip I can see my most recent were 24/12/21 and 29/8/21 so I'm guessing the latter is the previous version.
I will let you know the results . . . but I won't be doing this immediately.
Best regards,
John