Cumaru cupping issue — 3 months after install

Installed a 350 sq ft Cumaru deck in September. Client called last week saying several boards are cupping noticeably. The deck has solid skirting on three sides. I'm thinking ventilation is the issue but wanted to get some second opinions before I go back out there. Boards were at 14% MC when I installed. Joist spacing is 16" OC. Used DeckWise clips.