Unless they encrypted everything or you have some programming problem where your scanner isn't tracking the system properly it appears that all they did was rotate the control channel.
Try making a conventional system with all 10 frequencies in the database set to auto mode with no tone or NAC where it will receive everything digital or analog. If there is a setting that mutes encrypted audio turn it off. You will have to lock out the active control channel. Then see if you hear anything. Maybe it's just dead because of a holiday weekend.
If you don't hear anything but see lots of short transmissions then that could be OTAR or other data.
It's going to take somebody with Unitrunker or Pro96Com to figure out exactly what is going on.