@Ro – I am running Catalina and have no problems using the GS-R24 as the recording interface – it has always worked flawlessly and continues to do so. However, I have never used it in active fader mode, using the faders to either control or to mirror faders in software (I use Logic primarily). It just seems like it would be too complicated, and I couldn’t see how it would help my general workflow. So I can’t speak to whether that aspect of the mixer works under my current set-up.
And for anyone following the original question, I have purchased a Focusrite USB interface and am feeding the main output of the A&H into it and thus into OBS, all of which seems to work fine for livestreams in my initial test runs.
Thanks to all and all best wishes!