I have seen previous posts on this, but as it's well over a year since there were any posts, I've taken the forum's advice in starting a new thread.
I always fly in VR, mainly in the Fenix A320, but tend to do the MSFS flight setup bit in 2d and only enable VR once I've started the flight and am sat on the tarmac.
I use a Quest 3 headset, via Virtual Desktop, but I suspect that this issue will be the same regardless of hardware. It appears, and I am certain that someone will correct me if I'm wrong, as though the GSX Pro startup procedure, when MSFS is started up, looks for the sound device(s) selected in the GSX settings and if it can't find them at that point, it will then require a restart of couatl once VR has been activated.
The couatl restart does appear to work, as when I've selected the start boarding via GSX option in the Fenix EFB without the restart, the lady's voice does not tell me that the fuel truck is on the way, but after a single restart of couatl it works and thereafter the sound works fine.
I could also potentially work around this by loading MSFS when in VR and then dropping back to 2d again when setting up the flight, but I was wondering if anyone had found a more elegant solution?