You will see the Signal strength meter bump up as it scans through the Talkgroups. This is when it hits control frequency. The scanner will automatically lock out the audio on that frequency. If you did hear it all you would hear is data garble.
Make sure you haven't accidentally locked out the talkgroups. I noticed on mine even if I lock them out it appears that it is scanning them, but doesn't unsquelch.
FT-8900 | VX-170 | Home Patrol 1