I have done all this same thing as user above is showing... updates 1909 all fine but not been able to break out of that... I wouldnt worry minus the system is now telling me support on the version will cease in May. Below is what hardware we are running, both systems will not update, both running nvme drives. My wife has a B450 Asus but a traditional SSD no issue. I really am at wits end here...
I am running
Asus Crosshair VIII Hero X570
64 gigs ram
SB-RKTQ-1TB Main OS drive.
Ironically my Son has an
Asus x570 Strix Gaming-F
32 gigs ram
SB-RKTQ-512G