I think only PDFs show in the tabs (but not in the "preview tab, which is a formated reference according to the style selected in Endnote and is “text based” and doesn’t display images?). You would also need to save the figure to the file attachments rather than “figure” field.
You can always suggest additional ideas in the suggestions forum, but I am just a user. However, I use Evernote for that stuff and Endnote as my reference package. You can edit the an output style to show the notes, or choose, the output style: Show all to view text based items.