@Alan Freeman ,
Welcome to Q&A forum!
Removable USB drives are not supported.
< Removable USB drive, you could understand it as whether it is recognized as removable by Windows.
To move Onedrive folder to an external drive, you only need to set the SD card or other external storage source as an internal hard drive.
The link you provided has provided a method to convert the file system of the drive to NTFS as shown below.
If it doesn't work, you could also try the following steps.
- Press Win + R, type diskmgmt.msc in the run box and press Enter.
- Select the disk you want to copy>right-click>change drive letter and path.
- Click Add>Mount in the empty NTFS folder below.
Due to the limitations of the test environment, I cannot complete a complete test. Thanks for your understanding.
As far as I know, usually USB mobile hard drives are automatically recognized as built-in hard drives.
Beisdes, here is a troubleshooting document: Unable to sync OneDrive to an SD card or external USB drive.
Hope the information is helpful to you.
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