first off welcome to mixvibes,and Cross and U-Mix cntrol.
a little bit more info, primary sc
meaning the installed sc in computer
curious have you downloaded the vol control panel/driver for U-Mix Control, ,,what are the spec of your computer
,,,,in the drop down menue for selecting the sc/audio setup how is U-Mix reconiged /labeled as
need some more info to pin point whats going on and how you have it set up..
the software need the ability to have two signals sent(audio) one is the master the other is for cueing,, the U-Mix see both of thease signals and routes them accordinly, too use the primary sound driiver it must be able to process both siginals,ie multi channel sc,,so unless this is a multi channel sc then you are not processing the second audio siginal,,hences no headphone signal for cueing...fouces on getting the U-Mix Control Pro sc functional
again welcome
more info please
the volume control panel is installed when you download the latest driver package , the latency settings are still in the same location as in Cross ,preferences/audio,,the latency settings might curb the sound glitches but not the full soluton as to whats causing them will lead to the best solution,,goese back to what in background causing software to not having enough comp resources to run properly,thus pausing the software,that sound glitch is a kin to the hourglass/spining circle,when the computer has to catch up with itself 