Assuming you are scanning the system shown below, it is a simulcast system. Simulcast systems consist of multiple tower sites all transmitting on the same frequencies.
WQLM668 (CITY OF CHAMPAIGN/METCAD 9-1-1) FCC Callsign Details
Champaign County METCAD MDICE Trunking System, Champaign, Illinois - Scanner Frequencies
What you are describing is consistent with simulcast distortion, a topic having numerous posts in these forums. In a nutshell, your scanner is receiving transmissions from more than one site and it is having trouble decoding the signal. It is like two people talking to you at the same time and you have trouble understanding either one.
Simulcast distortion manifests itself by either no audio (as you described) or garbled audio.
Most likely if you were to take your scanner and drive to about a 1/4 mile of a site, you'll notice a significant improvement. This would be a good way of confirming simulcast distortion is the issue.
The key to dealing with simulcast distortion is just the opposite of what intuition tells you - you want to "lousy-up" your scanner's ability to receive. That's so it is receiving just one of the sites.
The following things can be attempted to improve this problem:
1. As mentioned previously, try moving the scanner around in your home. It's amazing how moving one just a few feet or re-orienting the antenna may make a difference.
2. Get into the programming for this system. Go to the site and set the attenuator to On (which dampens the incoming signal).
3. Get into the "hidden" menu. Turn the scanner off. Then, while pressing the Hold button down, power the scanner up (you'll see the display cycle through several colors). You'll then have access to the P25 Adjust Mode and P25 Adjust Level (Settings>P25 Adjust Mode and Settings>P25 Adjust Level).
You can tinker with these two settings and see if you come up with a combination that hits the "sweet spot" for your system. Unfortunately no one combination works for everyone. I use 13/175 for my local simulcast system, yet my neighbor with a similar scanner uses 11/173. It is all trial and error with lots of patience needed to work through this.
I'm sure by trying all these things you'll find at least some improvement.
Give them a shot and let us know what happens. There are some other things that could also be tried if they don't work, but the three things above are good starting efforts.