The issue started to appear since I updated to the latest BETA version. This was not present previously.
Steps to reproduce:
1. Start A-10C II - Enemy Within 3 campaign Mission 6 or Mission 7 (I have tested these, but probably all other will do as well)
2. Turn on Battery and Inverters, start APU, turn on APU GEN PWR
3. Turn on AM Radio, tune to frequency 133.000
4. Request startup clearence from Kobuleti tower
5. The tower will NOT give any answer
Solution to fix:
1. In mission editor, select the initial point of the player's flight, and edit the Advanced (Waypoint Actions)
2. Delete or disable the "Set Frequency(34.4)" action
This will resolve the issue.