Noel,
Thanks for the speedy reply.

I hadn't paid much attention to that column before.

I checked out all the String Quartet Real Tracks and find that those with shots and holds have a single 3 digit number (e.g. 295).
Those that have shots only have a 3 digit number followed by n (e.g. 295n).
This goes some way to explain the issues I have, but I still reckon there is something wrong with RTs 2510 & 2511.
I also notice that the "Held" option is greyed out when an "n" number is selected, so there goes my idea for a work-around.

Best regards
Vintage