Can record cc8 on VSL violin track, but not on viola or cello

OK, heres a real stumper. Ive composed a string trio and am using VSL Solo Strings (I have the VSL expression maps) for the violin , viola and cello. I use my Sparrow midi fader / controller to record cc8 messages (timbre) on the first violin track just fine.

BUT when I switch to the viola, when just playing the track I have control of the on screen (Synchron Player) timbre fader, but when I go into record I dont.
Ive checked midi routing and channel assignments and compared the violin (which works) to the viola (which doesnt) and after experimenting cant come up with a solution why only the violin channel will record CC8 messages from my external midi controller and the viola and cello wont.

Are you hosting the Synchron Player directly in Dorico or in VEP?

EDIT:
I had no problems doing this with Synchron Player in Dorico…
When adding CC8 to the Viola, make sure you initiate Recording from a note selected in that instrument, etc. … :slight_smile:

Thanks! Problem was solved but couldnt delete.