That bug report seems to indicate that it is to do with the Mount Manager and maybe rclone is discarding the special path \\.\S - you don't seem to be using that path in the example above though?
Something you could try is mounting it on a directory instead of a drive letter, so instead of S: choose an existing but empty directory say C:\gdrive and use that instead of S:
If that doesn't work we'll have to call in the experts - @albertony is good at Windows file systems.