Skybolt - I'm trying to get the @signalk charts...

I'm trying to get the @signalk/Charts-plugin web app to work. The resource plugin points to valid reference /signalk/v2/api/resources/charts and the charts plugin works fine pointing to /home/skybolt/.signalk/charts. SK-Freeboard sees the charts just fine. The charts are mbtiles downloaded from the NOAA site and seem to work with everything except this plugin? Any thoughts?