Just gone from heaven to hell (and back to heaven) with a couple of errors - first of all "Fatal error" then "Pass your message" (US: Go ahead).
So I thought I would share the solutions in case of anyone having the same problems. I am on FSX-STEAM on Windows 10. Stock 172.
Very new to the VOXATC software, but very impressed. A real game changer, and significantly closer to reality then the FSX ATC.
Fatal error
No doubt can be caused by a number of things, but in my case it was installation of Ivona voice pack British Brian. I don't know why, because others have praised these Ivona voice packs, but extensive installing, uninstalling, testing every permutation did seem to prove it. It was the best voice I came across, but it did cause continuous Fatal errors. Problem gone after uninstalling
Pass your message
When I first started using the software I had close to zero problems with ATC understanding me. I did the couple of quick voice recognition trainings as per the manual, and I was off. ATC understood what I said 95%+ of transmissions.
But after having solved the Fatal Error problem above, I was left with another problem. Suddenly for everything I said the ATC answer was "Pass you message". Finally, I uninstalled a load of other (non-Ivona) voice packs which I had been trying out. They were not active on VOXATC, but installed on my PC. Bingo, we were back to ATC understanding everything I said
Can't say I understand what is going on, but it's taken me a lot of hours to work out what I have, so hopefully it can benefit someone else too.