Thanks for letting us know what worked for you! I went ahead and flagged you post as the solution.
As far as automatically adding / removing the leading slash, that’s probably programmatically but too hard but it may not be the “right” solution.
For example, some people have asked how to make their backup files NOT show in the general file area. So it might work better if we somehow add tooltips, help, or an alert letting users know when a path choice might result in their backup files ONLY being visible to Duplicati.