I inserted an SD memory card into a USB card reader and plugged it into my PC. I got this message:
I knew something's not right because I just pulled this card out my laptop's built-in SD card slot, and the card was readable there. I fired up my laptop again, and indeed, the data on this card is perfectly accessible. Then I took another USB SD reader and that, too, lets me access the files no problem.
However, it's not simply the case of reader #1 not working. It does work with other cards I tried.
What's going on? Why does the same card work in one reader but is "not formatted" in the other?
P. S. It's a FAT32 64 GB card with 64K cluster size.