Are you always using an expression pedal to control the output volume of the entire FX Chain? If so, I would suggest mapping it to the FX Chain output gain parameter. Click the green I/O bar to expose the FX Chain parameter (In Gain, Out Gain, Mix, etc.) and you can map the output gain parameter there. The output gain of the FX Chain has a finer resolution compared to the algorithm output gain parameters and this may work better for you.
