I'm breaking a B67, and have a similar problem on occasion.
This all might be related to insufficient break-in as opposed to a problem with the tilt.
"They" say to tilt the saddle so that the middle is the lowest point on the top surface; that way one's butt doesn't slide too far fore or aft.


My plan - if the problem persists beyond the break in period - is to consider sending the saddle off to Selle An-Atomica so they can cut out the center. Before I blow another $50 with it, I want to be sure it is necessary.
Meanwhile.....I might give the thing another oil treatment on its underside.