Comment by sobellian

I used CP-SAT to enumerate the solutions. A heuristic for "interesting" solutions is those which only admit one valid bishop placement. For example:

    ........
    Q..B..Q.
    ........
    ........
    .......Q
    ........
    ........
    ...Q....

Where the bishop lies at the intersection of three queens' horizontal attacks. With these queens, no other bishop placement works.