I just added a supermidi track to the melody track of a Real Track Style song (all RTs).
And I added a custom midi style to the soloist track.

Workflow: Right Click on the empty track in the mixer (Patches). Select options... done

I am now convinced it is workflow. There is a right way to do it and a wrong way.

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BIAB – 2025, Reaper (current), i7-12700F Processor, 32GB DDR4-3200MHz RAM, 1TB WD Black NVMe SSD, 2TB WDC Blue SSD, 1TB WD Blue, 2 TB SK NVMe, 6 TB External, Motu Audio Express 6x6