Firefox can't detect microphone if plugged in while it's running
So I've found that Firefox doesn't seem to detect my headset microphone if it's plugged in while Firefox is already running. Going into a Google Meet meeting, it asks me if I want to allow the use of my microphone, and only shows a device that was plugged in already (a Rift S headset microphone) - unplugging, replugging, and refreshing the page all have no effect.
If I close down and restart Firefox completely with the headset plugged in, it works.
After searching, apparently there was a similar bug that appeared around Firefox 36 (I think?) that was fixed soon after - In any case, it seems to have reared its head again.