No, I've only Start11 v1.22 installed.
I just restarted my computer and it's behaving correctly again now with two screens. I've opened my usual group of applications and working. So there's something happening here but replication not easy.
Next time it happens I'll record it and share.
Very frustrating when you can't maximize applications from the taskbar as makes Windows difficult to use with multiple applications opened.
Ah ok just had it occur there again and I closed the one application I suspect Microsoft Teams and everything working now again. Need to dig a little deep, could be just a coincidence, re-opened Teams and everything still working...