Hello Nigel,
I don't have experience with the Friesach sample set myself. Are you referring to:
a) The General Cancel button, and combination buttons (master generals, etc.) on Hauptwerk's control panels (such as the Registration large control panel), or:
b) Virtual Pistons (a cancel piston, and combination pistons) that are embedded within the sample set's graphical virtual console?
[If a) then it's conceivable that Piotr Grabowski (the sample set's maker) didn't list the virtual stops in the organ definition table that tells Hauptwerk that they should be affected by Hauptwerk's combination system, but I'd think that very unlikely.]
Please try:
- Right-click on the relevant virtual General Cancel piston/button and select "MIDI key/trigger settings ...: Clear all (for all organs ... and also for this organ)".
- Also do likewise for at least a couple of the virtual stops (using the "Clear MIDI key/trigger settings for stop ..." entry).
- Turn those particular stops on, using just the mouse.
- Now try clicking on the relevant virtual General Cancel piston/button using just the mouse.
Does that cause those stops to be cancelled?