I've searched on here and I see way back in 2011 that people used to have trouble getting ATC to respond. I'm having the same issue.
I tried a Single free flight mission starting on the ramp. I also tried the Aircraft Startup training mission just to make sure I wasn't missing steps.
For both, I'm up and running with APU on, AC generators on, radios on.
For Batumi in the training mission I'm tuned to 131 MHz
For Senaki-Kolkhi in the free flight mission I'm tuned to 132 MHz.
Easy Comms are on.
When I access the ATC menu in the free flight mission /, F5, all the airports are blacked out. If I request Engine start from Senaki, ATC never responds. For the training mission, none of the airbases are blacked out but Batumi ATC also never responds. Still on Easy Comms.
I also tried it on the first mission of the Georgian Hammer Campaign. There the airbases are still blacked out but Batumi ATC does respond. This seems like a bug. I only tried it once in the campaign so far so I don't know if the issue is intermittent or if it works on some missions and not on others. Does anybody else have problems with this and is there a solution? Thanks for the help.