There should be an option to not use the Media Browser when you are in the "Rellocate" windows. So instead of the Media Browser, the regular Finder/Explorer will be prompt instead, and from this window you should find your external drive.
There should be an option to not use the Media Browser when you are in the "Rellocate" windows. So instead of the Media Browser, the regular Finder/Explorer will be prompt instead, and from this window you should find your external drive.