Stealing Chords and Scales from a MP3 converted to Midi

Ok…so I take the mp3 I like. I’ve converted it into a midi. Unfortunately I get a mess of instruments in one track when I import it into Cubase. That’s ok. I know that a midi converter cannot split the instruments in a MP3 file into separate tracks.

All I want to do is create a Chord Track…play the track and I’m confident I will get close enough to what the chords and scale are…and then I can go from there.
The problem is unlike when I play live digital piano, the chord track isn’t writing chords and/or scales for me when I just ‘play’ the imported midi track.

Is there a way to get the chord track to write the scale and chords like it does when I play live?
Is this something that is even possible?

Found it in the manual…I know stuff is there…but it can be painful finding it. At least it works.