Some of the aircraft in MSFS 2020 are not properly maintaining the Radio Power status in SimConnect. This will result in FS-ATC-Chatter not playing chatter if you have the FS-ATC-Chatter radio power option enabled. To work around this disable the radio power option on the Radios setting page.
Please let the aircraft designer know they should fix their aircraft so that it properly maintains the SimConnect radio status.
