It’s very minor, but if I touch the first note of an imported MIDI piano track, a brass patch plays. Then touching P (play), the piano track plays its normal patch. Seems like this could be easily fixed.
Try to reapply your playback template: menu Play/Playback Template… choose the template that you want (the ones with HSSE, depending on your Dorico version, or Note Performer, if you use it, or any other that you created), click apply and close. So Dorico recreates the midi channels connections (or something like that ) and all should be ok.