[QuattroGam3r]

Had the same thing happen to me on my Pi2.
Finally edited the settings.xml for this add-on to remove the / from the end of the path

Code:

From
<setting id="artwork_folder_path" value="smb://NAS1/Volume_1/Multimedia/MovieSetArt/" />
to
<setting id="artwork_folder_path" value="smb://NAS1/Volume_1/Multimedia/MovieSetArt" />

And all worked perfectly.

But, would be better if the addon was fixed....

Glad that worked for you, when I tried it there was no change on next run. That's why I dove into the python script.

Agree, would be nice if add-on was fixed or maybe even merged into Artwork Downloader.