Fixing screw shear on 5/4 Ipe boards over stainless joists

Running into a recurring issue on a high-end Ipe job in South Florida. I am installing 5/4x6 Ipe over a custom stainless steel sub-frame using Grade 316 stainless screws. We are hitting the joist with pre-drilled holes, but the shear force from the Ipe's expansion is snapping heads off at an alarming rate during these high-humidity shifts. I have tried switching to a slightly longer fastener, but it is not helping much. Has anyone dealt with this specific metal-to-hardwood movement issue before? I am considering switching to a clip system like DeckWise, but the architect is insisting on a face-screwed look for the perimeter boards. Is there a specific high-tensile screw brand you guys trust for steel-to-hardwood connections that can actually handle the seasonal torque, or should I start spec'ing oversized clearance holes in the stainless?