My GoPro Hero 3 black has now done this to 2 of my SanDisk 64gb micro sd xc’s…
No longer under warranty… I take it niether GoPro or sandisk are gonna address the issue / provide refunds…
i’ll try non-Sandisk when I go spend mo money on a new card…hopefully doesnt happen again… these cards being $50 CAD I hate to have to be buying new ones to replace faulty ones…