Typically to set up scenes I will select my parts (instruments in the band) and then select which instruments are to play in Scene 1 by muting the ones not needed in that scene. Similarly for Scene 2, 3, etc.
I do this from the performance home screen and then press Shift/Scene to store to the relevant scene.
I understand that this can also be done using keyboard control, which conveys some advantages.
This appears to work most of the time, however I have found that sometimes I need to go the route of selecting the "mixing" tab and then turning on the mixing button and then set scenes from that screen.
I spent some time trying to set scenes in a particular performance with the first method, without success, I then found that it easily worked via the second method.
If someone could explain the difference between these two methods I would be most grateful.