That's interesting. That must be the reason for the disappearing audio that people have reported. It happens to me quite often when I pause on a TG. I notice that after a while there is a lack of activity and if I scan with another radio I realize that the TG is still active but the radio is no longer tracking it.
I have it set to check the cc in scan mode so it will check them all in case they switch control channels. As mentioned you can check in manual mode when you analyze the TSYS.