@john-phd I've had similar problems with my Opera sound playback so I wanted to share what worked for me in solving it. You mentioned having multiple audio outputs and I had ended up with a similar situation when messing around with a selection of audio software and virtual audio cables and the like.
My opera wasn't showing up in the standard Windows volume mixer when sound should have been playing, so I went to the Microsoft Store and installed 'Ear Trumpet' as a 3rd party alternative. Once launched, I expanded the list of sound sources and I could see my Opera sound was being directed to something other than my main speakers, hence no output. Right-clicking on the Opera icon in that list and then clicking the icon with 2 sideways arrows allows you to redirect the output to whatever source you want. In my case it now works again just great, and I can see it in the Windows volume mixer as well once again, so there's no need to keep Ear Trumpet installed if you don't want to.
Hopefully a similar easy fix might have been at the root of your own issue? Or anyone else who stumbles upon this thread looking for answers.