Well, I really did not think that I was dealing with some hardware incompatibility.
On a fresh account all taskbars are present.
The question becomes what among my very many other pieces of software has an issue with Start11V2?
It would take weeks to start from the beginning and slowly re-install everything and tweak each setting until I might find the errant interaction....
Or I can set Windows not to show a taskbar on secondary monitors, which appears to be the less time consuming approach.
If you have any better idea, please let me know.