[SOLVED]
So I figured it out what was stopping TGS.exe to start.
When TGS was working I did start PF3 myself but then, for convenience, I put it in the FSUIP7 ini file so it would
automatically start after FSUIPC started and got confirmation that MSFS was running.
When I reverted back to manually starting PF3 then TGS is working fine again.
Kind of strange everything of PF3 is working fine except for TGS when it's started automatically by FSUIPC7
I guess has to do with executing "rights".
Anyhow, problem solved, up to the next one

Thanks,
Luc