Video by PG Music Inc. via YouTube
Source
If you are starting with a RealStyle and want to make one of your tracks a MIDI track, a MIDI patch cannot be selected for a RealTrack. This is because RealTracks are made from audio recordings. Instead, the MIDI Track Picker dialogue is used to replace a RealTrack with a MIDI track. This video is demonstrated in Band-in-a-Box for Windows, but the steps are the same in Band-in-a-Box for Mac.
If you are starting with a RealStyle and wish for all of your RealTracks to be MIDI, then we recommend to select a new MIDI Style from the main Style Picker window.
Here is also an overview of the StylePicker window: https://youtu.be/g9Ovdul7bi0