I had the same problem. It is the same issue as the screws on the Interstate. Stick a putty knife between the two haves and pry as you turn the screws. When you get it apart you will see that the screws go into a brass ferrule and the ferrule is turning with the screw. JB weld the ferrules back into the plastic and you will be good to go.
Brad
Verrrry interesting. For interstates, this is consistent. When removing the fairing/shield, the anchors up there are known to spin in the plastic too.