I have 4 Design Spot 250s. When the Grand Master is pulled down on our SD3, 2 of the 250s pan & tilt and the shutter closes. The other 2 just dim like they should. I have tried copying one fixture to the other but no difference. The only difference I see is that 2 of the fixtures are on output 1 and the other 2 are on output 3. Need some advice.

It sounds like those channels are tied to the grand master. From the modify fixture menu, go to the grand master control for that problem fixture and make sure only the dimmer channel is selected.