It simply seems like the Unidens "trunked priority scan" is unable to read the subaudible or control channel data while monitoring an active talkgroup, like a "real radio". It would be hopeful that uniden, with software defined radio, could add this function, unless there is some proprietary licensed technology involved. On my 996's, on analog trunked receive, you can litterally hear the trunking growl really low in the background, most audible right after the channel drops.
Paul