Not in front of my Axe but check EQ Page to make sure there is no hi cut (and maybe also low cut) or other EQ contouring.
Also check that ducking is off: "Ducker Atten – Attenuation sets the amount by which the effect volume will duck (decrease). A setting of 20 dB, for example, will decrease the reverb by 20 dB when the input level is above the threshold. Set to 0 to defeat the ducker."
This also might make a difference: "Crossover Frequency, Low Frequency Time, High Frequency Time – The reverb algorithm is actually multi-band, reflecting the way that sound energy dissipates differently in real spaces. This allows for very natural effects. These parameters control decay times for the two bands, plus the crossover frequency."