Thanks for testing. After trying to get documentation (this is Windows Vista era, and seems to be
fading away), I’m thinking that its available controls might not bear much similarity to OneDrive’s.
The Windows Drive Letter Problem has a possible solution to detect not-really-there destinations.
--alternate-destination-marker (String): Look for a file in the destination
folder
This option only works when the --alternate-target-paths option is also
specified. If there are alternate paths specified, this option indicates
the name of a marker file that must be present in the folder. This can be
used to handle situations where an external drive changes drive letter or
mount point. By ensuring that a certain file exists, it is possible to
prevent writing data to an unwanted external drive. The contents of the
file are never examined, only file existence.
If that’s not sufficient, but there’s still some way to tell, you can write your own run-script-before.