do you meandownload to your PCor upload to HCIf it is #2then...

do you mean

1. download to your PC
2. or upload to HC

If it is #2
then they may be

• to large
• copy to other site restricted
• wrong format,,,as in some people put more than on extention on ( .jpg.gif or .tif.jpeg )

You may need to reformat your new SanDisk,,, most are still fat, your need NTFS

Try a diff USB port, check your usb ports to make sure you have not killed it,
you must ALWAYS STOP A plugged in device afore you pull it out,failure to do so can kill the port

Go to you control panel,find usb ports, check that they are working,unistall and reboot

Win 10


Win other