when you say you usually position seats back anyway, could it be that like in my case, it was just a bit too far back?
the one that had the weird "crease" rubbing was then on my dropbar bike, a Specialized Tricross with maybe 2 1/2 inches of seat to bar drop. After I resolved the rubbing issue on the right side, I ended up taking it off and putting it onto my mtn bike/commuter because I found the used one. I put the used B17 onto the Tricross and because of the lower handlebar position, I have it more level than the B17 on the mtn bike that has maybe 1 inch of seat/bar drop. Im the same weight as you.
Hope you can get it sorted, if not, its just a bike seat, you can sell it (and I'd be interested!)
Even with current saddle position I sometimes slide back a bit for harder efforts. If I put saddle forward it seems that thighs would rub even more against the wider portion of the skirt which seems to be the bigger problem than the nose. Seems like Brooks just have weird shapes that work great for some & bad for others.