If you scan the system, it will decode to unitrunker just fine. But when your scanner finds a talkgroup and monitors it, the control channel will be replaced by the conversation, adn unitrunker will stop decoding.
When the conversation is over, the control channel returns and unitrunker will decode once again.
You can get a second scanner, use your tapped scanner to run unitrunker and just leave it on the control channel, and use the second scanner for audio... it being controlled by unitrunker.