Discovered that if you switch frequencies whilst ATC is still transmitting something it will just break after. It'll just continue putting the last transmission in view about every minute adn you aren't able to contact ATC/ground crew/JTAC anymore.
Happened to me before in 1.2.6 and again in 1.2.7
Encountered with the A-10 and KA-50.
Also it seems that it does'nt fix after a reconnect, not 100% sure though.