Because some aircraft and/or plugins don't bother to clean up after themselves, the following datarefs should be force-enabled when appropriate:
sim/cockpit2/radios/actuators/com1_power
sim/cockpit2/radios/actuators/com2_power
…it's already done for e.g. sim/cockpit2/switches/avionics_power_on (which is perhaps a more common source of errors, but the above being set to zero can happen too).
Regards,
Tim