Cubase 8.5. I set Cm scale, choose Chord Track Event colors in the MIDI Editor, now A# is colored red, it means that it is out of the Cm scale. I’m not good in the music theory but I think that there’s something wrong with Cubase.
Please, could somebody check this out and reply to me.
Thanks.
Not in front of the DAW at the moment but from a music theory point of view this could be argued both ways.
A# (enharmonically Bb in equal temperament) is the 7th of the natural Cm scale.
However, it is NOT in the scale of the harmonic Cm.
Even more confusingly, it is not in the scale of the melodic Cm ascending BUT it is in the Cm melodic scale descending.
So, depending which minor scale you are using (and whether you are ascending to or descending from the 7th) depends whether Bb (enharmonically A#) is IN or OUT of the scale.
Thank you very much. I’ve found my scale - Natural minor, now everything is fine. 
Why not just play the notes you want to hear? All this “Chord=scale” business is really only a cop-out for wannabee improvisers (guitarists seem particularly prone) who can’t think of anything melodic to play.