okay, here is my 2 cents worth - okay maybe 3 cents.

#1 - considered lowering your saddle height a smidge, I know you had a bike fit but that isn't always cast in stone.

#2 - not congruent with #1. loosen your seat post and turn the nose of your saddle slightly off center to the left. You may have a slightly tilted pelvis or a body geometry that isn't asymmetric so you hit the saddle differently on the left side than the right, if that feels wrong than turn slightly off center to the right.

#3 - play with sliding the saddle back a smidge - a B68 is a wider saddle and maybe being back a smidge will change your seat bone position and the angle of your leg.

I rode the B17 imperial for a bit last fall and winter and realized the long sides/fenders/skirt - what ever you want to call it was not something I liked. I felt like it impedes my leg movement and I found I felt more numb in the upper legs and rear on a long ride. Put the Rivet Independence on about 2 months ago and the problem went away.