This really seems weird, please try to isolate the channel on the right on a different VCA group and check if the problem persists.
The channel CUT on VCA consoles is triggered with the VCA voltage higher than 7.5v.
This is done through a small circuit parallel to the Sample and Hold circuit which is comprised of a transistor and a capacitor if I am not mistaken, which enables the fast ramp voltage to trigger the CUT on the console in a very short time (something the sample and hold is not capable due the heavy filtering on the output).
Check this circuit and see if you don't have any chips with problems that are mistriggering the cuts, induced by a neighboring CUT.
I would start by measuring the VCA computer return and trying to find a pattern.
Good luck!
Cheers,
Artur
