My PC won’t recognize my cards at all. They work fine in the devices I use them in. Plug them in to a card reader and it’s like they aren’t there. Any help is appreciated.
You might need new(er) card readers. The 64GB cards are the SDXC format; different from the SD & SDHC of the smaller ones. Not all card readers will read them.
I just bought a new dynex reader. I have to admit though that I didn’t thnk the reader made a difference.