First off, let’s ensure that your PL/DPL code are correct as well as your frequency.
Once that’s out of the way, disable MDC unless your agency/department uses it. Otherwise, it’s really just a senseless data/id burst. Sounds like you have the channel checked off as a constant talk-about frequency. I believe this can be disabled under zone channel assignment, scrolling all the way to the right. If you want to be able to use the frequency on TA, enable a button to turn TA on and off on any frequency. That’s the best bet