Hi Jack,
Hmmmm! That's everything I can think of and you've done them all...! Looks like a case of hoping that Microsoft fixes the issue with the updates ASAP..!
I've upgraded 2 laptops in my house to the latest window 10 version 2004, (the other PC's have a message saying they won't update yet!) But from what I'm reading it wouldn't make any difference. Its definitely not a brother issue as everybody and yourself agrees, especially if you can print from your phone!
The only (and it's way off and a longshot - a very longshot...!!!!) If you can upgrade to version 1909 or 2004 then see if those kb's are installed and you can uninstall them...! But thats the 3rd glass of whiskey I've had that's talking!
Finger and toes and anything else crossed for you and other people that haven't been able to fix the issue!