Now I thought it was just me. I have PU solo and the OEM fender rack. I thought it was the combination of the bolt heads and the rack from keeping the seat from latching. I used a pair of pliers to persuade the bracket into a slightly better position. I still have to use a little pressure to get it latched up but once its locked its on there solid.I just mounted the PU wide pillion to the PU solo seat... the pillion was easy to mount, but I had a heck of a time with the solo seat getting it to "latch" under that tab and then click and lock into place.
Did you have any difficulties?