I think I've either misunderstood how to generate RealTracks from an existing song in RealBand or something has changed since I upgraded to 2020.
I have opened an existing song MGU BB file into RealBand 2020. The song generates its tracks as normal and the song plays just fine.
However, when I attempt to select a portion of a new track and the Generate RealTrack on the selected portion I get a display that I have no RealTracks to choose from. The display is attached. I thought perhaps it was that RB did not have access to the RealTracks folder, but this is OK. I have had this working under previous RealBand versions so maybe something is wrong in my setup.

On a related issue, when I try generate a midi track, I am told that the selected instrument is not available in the current style. Does the instrument have to be in the current style? I though that it was simply the chordsheet that was used in conjunction with any style that generated new track section.

Any ideas please?