hey Griff,
I assume you mean when you roll off the volume on the guitar to clean up the gain. Just like the others have said, I find that the 11R models of my amps roll off just like my actual amps do
I do use a little gate however, and that does not seem to affect things.
That said, I'd look at the gate first, as that tends to be the easiest to diagnose. Then look at the wireless. It is possible that a less hot signal from the guitar to the transmitter COULD cause some thinning by the time it gets to the receiver.
I don't use pedals anymore generally, because I find the FX within the 11R to be what I need. But, I have tried my very old rusty and trusty Foxx Tone Machine with 11R for grins.
I found that it sounded best in the FX loop instead of going guitar, tone machine, 11R.
I don't know if that helps, but just my experience.