Is the card a 32 gbyte or less in size? Roku does not indicate (that I can recall) an upper limit on
the size of a card, but I would not use anything above a 32 gbyte BRAND NAME card. Next, I found it necessary to do a 'hot' install of the SD card to have it recognized by the Roku box. That means have the box up and
running without the card inserted, then install the SD card with the box running and powered on. Being in
a powered up state was the only way to get the card recognized with my Roku box. After that, the format
of the card should follow with an automatic menu driven operation . Hope that helps.