I had installed this plugin last year and layout was that thumbnails were on left, and the main image being viewed was on the right. I went to update one of the galleries today and all of the galleries are broken.
When simpleviewer loads, all of the galleries just show a horizontal row of thumbnails.
I updated the latest version 126.96.36.199 and have WP 4.7.2. I did try deactivating all other plugins and switching to the default twenty fifteen theme. Nothing changed.
I've tried changing the gallery style, thumb position, and several other options and no option setting makes any change at all in the front end.