Hi there, based on your problem and all your attempts, you can exclude the drive error directly. Instead, you're recommended to check if you have set all your files hidden on the drive previously.
Frankly, if you made your files and folders stored hidden, then you can't see files on a USB drive on Mac. Therefore, all you need to do is make them visible again via the Terminal app.
Step 1: With the external hard drive connected, you need to launch Terminal first.
Step 2: Enter the following command, leaving a space at the end, and don't press the Enter/Return key yet:
Step 3: Drag the flash drive icon on your Mac desktop to the Terminal window to insert its path.
Step 4: Switch back to the Terminal and press the Enter/Return key.
Step 5: Enter the following command in the Terminal window.
chflags -R nohidden *
This method should show all hidden files on the entire flash drive. Hope you good luck~
You may also be interested in this article if you meet the SD card files not showing on your Windows or Mac computer: How to Fix SD Card Files Not Showing Up on Windows and Mac?