Building code issues with Ipe in WUI zones — need help

I'm in a California WUI zone (wildfire urban interface) and the building department is pushing back on my permit for an Ipe deck. They say "wood decking" isn't allowed. I've provided the ASTM E84 Class A fire rating documentation but the plan reviewer doesn't seem to understand that Ipe is fundamentally different from cedar or pine. Has anyone navigated this successfully? What documentation convinced your building department?