Blackmagic SD Card read fail

I have 4 SD cards (2 x 128GB and 2 x 64GB) that all have footage recorded onto them using a Blackmagic monitor. When I insert the SD card into a reader (I have tried a few different readers) I get a format disc prompt. When I click cancel it says:
"The volume does not contain a recognized file system. Please make sure that all required file system drivers are loaded and that the volume is not corrupted"
Though my main computer is PC, this happens on both PC and MAC.
I have tried FileSafe and HFSExplorer to no avail... I cannot figure out what is happening. There is probably something I'm missing. Deadline for broadcast is looming... help!
"The volume does not contain a recognized file system. Please make sure that all required file system drivers are loaded and that the volume is not corrupted"
Though my main computer is PC, this happens on both PC and MAC.
I have tried FileSafe and HFSExplorer to no avail... I cannot figure out what is happening. There is probably something I'm missing. Deadline for broadcast is looming... help!