GSX Pro has no sound, actually. I already reload the couatl thing and looked into settings. Nothing has changed. But I don’t have sound from GSX Pro. All other sounds were available, and now I got never ending loading by GSX Pro menu on top.
And now GSX Pro Menu wont load anymore? I got the infinite loading now for 6 minutes.
I guess it is too late for a refund 
The vanilla pushback by Asobo is not so extremely prone to errors like GSX Pro and it is for free too resp. included.
Another few minutes later GSX Pro is back, but the sound is still gone. And they offered two options for pushback service which is new too.
OK i give up with GSX Pro.
Usually just going and restarting couatl is all you need, and that for me has fixed any issue I have with GSX. For me so far the only sound issue I have is if I accidentally have the sound set up to use the wrong device in GSX settings (monitor instead of headphones or vice versa). In your system tray on your taskbar you will have an icon for couatl and you can just right click and hit restart. Should clear up any issues.