It should also be noted that A&H typically sets up their consoles so that the mute button will mute ALL outputs (including any “monitor” outputs). I don’t have a CQ to ensure this is how the mutes work on this system, but I would be shocked if it was any different from the other A&H systems.
This means if FOH needs to stop a signal from going out of the main outputs, but still allow the musicians to hear that input, they need to use the fader (lowering it to – infinity) rather than muting the channel. In addition, they would want to ensure the monitor auxes were set up “pre fader”.