That's probably better to ask on the Mac side of this forum. Adv. SS is probably working exactly as you need now.OBS isn't always pulling the Stream automatically, respectively doesn't always show the image of the Stream altough Audio is showing up from the Stream. I don't know, if this a Bug from OBS (using OBS 29.1.3 64Bit, with Mac OS 12.1)
Remove everything you can and still keep the problem, and then ask over there about your pared-down demo.