In the latest official release (0.6.1) there is a bug that occurs if the (P25) Talk Channel is outside of the range of the dongle. Happens with Airspy R2 and RTL-SDR V4, for example on different laptops.
In the 0.5.X versions (that I plan to upgrade from) there was a normal and relevant Missing Tuner error that occurred if the Talk Channel is out of reach.
In 0.6.1 (and perhaps before) if the Talk Channel is out of range, the abnormal and irrelevant Max Traffic Channel Exceeded endlessly appears in the lower Now Playing Details column of the lower pane, and all the Talk Channels (within or outside the range) stop appearing in the Now Playing upper pane, and no sound is heard.
This is not related to the Max Traffic number in the Channels tab.
To reproduce, Stop the active Channels, decrease the Sample Rate in the Tuners tab to not cover your whole P25 system, and Play the relevant Control Channels. After a less than a minute you will notice the issue.
Thank you,
Noam