usb stick

Make sure the thumb drive is formatted with a file system Apple recognizes. Use Disk Utility to erase the thumb drive. You may need to click on "View" and select "Show all devices" before the physical drive shows up in the left pane of Disk Utility.

Some thumb drives just don't work on a Mac. The quality of thumb drives even from reputable manufacturers is not always the best.

Go to: Finder > Finder Preferences > select the Sidebar tab and make sure that the External Disk box is checked.

Go to: Finder > Finder Preferences > select the General tab and make sure that the External Disk box is checked.

If those are already checked, try a different USB Flash Drive/Thumb Drive.

Keith Barkley wrote:

The Mac understands many "Windows" file systems, especially the FAT ones. About the only one you may have issues with is NTFS, and I believe you can read those.

FYI, macOS cannot understand some larger ExFAT block sizes when Windows formats the drive. If you want to use ExFAT with a Mac, then it is best to have macOS format the drive.

macOS doesn't deal well with anything unexpected or out of the ordinary. I've also had issues with some USB sticks not working between different versions of macOS. The flash drive is most likely the culprit.

The Mac understands many "Windows" file systems, especially the FAT ones. About the only one you may have issues with is NTFS, and I believe you can read those.

I have to agree Keith and suspect that there is something else wrong with the Flash/Thumb Drive or the way that the film was put onto it.