I go to 'effect' to right of 'filter' and change the lower element to 'hard distortion+lowpass' with the amount =0%. I get a noticable volume increase on the patch even with it having an amount of 0%.
Other observation.
The filter reso knob shows noticeable decrease in gain when you increase the reso. Is this by design? Can you increase the volume or keep it the perceptual same when the reso is actuated?