As everyone is waiting with bated breath for my latest update, I better update you. I unplugged the monitor and left it for a minute before plugging it back in. This time I saw the three "loading" dots onscreen and thankfully the sound is now working 100%.
It may just have been a coincidence but the wobbly happened when I opened up FaceTime. A continuous tone almost like an alarm sounded and video completely froze. FaceTime hung and I had to Force Quit it. The continuous tone continued until I rebooted the Mac Studio. On trying FaceTime again, the video was very jerky. Sound was a complete mess. In short, perhaps the monitor got stuck while doing an undocumented firmware update.