Hi, I’m a pretty good musician but a rotten engineer. Thanks for the patience… I have a QU-16 and Logic Pro X. I record my band on individual tracks with my 2009 El Capitan iMac. Tracks sound great as a group. BUT when I try and solo a track to isolate an individual instrument, the volume drops out entirely. So, playing all tracks of a song works fine, solo on one track (Logic Pro X) causes all the sound to stop, though I can still see the track waveform and the track bar moving across it, and the levels go up and down. I don’t know whether I’ve got an issue with mapping/routing/patching on the QU-16… ( I really don’t know what I’m doing but I did install the DAW controller and it seems to work at least not he record side) … OR do I have an improperly configured Logic Pro setup. I pursued the Logic Pro side until I ran out of ideas. I’m sure this is a simple thing but I’m a player, not a studio engineer. Can someone prompt me with some ideas? And please use the small words - I’m awfully new at this. Thanks so much.
Check your options and level per p. 56 of (wait for it)…the Manual:
If you’re talking about soloing within the DAW there’s another Forum section specifically for DAW issues.
Ok, moved.
Basic question obviously is: Where do you select the track to be soloed?
If this is inside logic, then I suspect that there is some setting which routes the solo signal to some different output, not necessarily those which you are using for regular playback.
Just guessing, hope someone actually using logic can help.
I actually have the same problem. If I hit the solo button - Everything goes silent. 
Very frustrating!