Your firmware and app are the latest versions.
Firmware 1.8.0 and App 5.16.
I never use the touch on / off on mine (I always use the app) so I can’t help you but, it should work.
Is the power button lit on your Qb?
Is cleaning mode still a thing on the QB? If so, this could have been engaged (but can’t remember how to disengage it - probably from the app.)
I have the same issue with my muso 1st gen. It’s been like that for last couple of years, and I power up using the remote.
All other functions on the wheel work as intended.