Yeah, sounds backward. Usually I ice the breast but that's because the breast usually gets done before the dark meat.
Can't imagine what is causing your issue.
There's certainly nothing wrong with cooking breast side down.
The dark meat usually needs to go a out 10 degrees more than the white, so that's why it's a good idea to ice the breast to give the leg & thigh a head start.
18.5", 22.5" OTS
Large BGE (chambersuac's)
The Fiery Furnace (chambersuac's)
Big JT's Smokin' BBQ Competition Team