Yesterday i tried to import tracks from another C12 project to a new one and it only creates them but doesn’t copy the audio files or markers that were on the marker track i also selected. I tried that with same project in C11 with no luck and finally did it in C 10.5 which is really weird. I’m on latest W10, C 12.0.40.
Make sure to have the boxes ticked in the import dialog…
All checked. Everything was set up the same way in all three versions, but worked only in 10.5. 
This is still a bug and it’s not working in C12 and 11. Only in 10.5.