Hello,
I created a new clean installation of WP to test where the problem was.
What i figured out is that it depends by the template. No other plugins installed, just ‘my’template plus the default of WP and Portfolio Gallery.
When i switch the theme the plugin stops to work (blank page or all the images one below the other) and i see this JS errors inside the console:
SyntaxError: expected expression, got ‘<‘
var lightbox_initialHeight = ‘100’;</p>
SyntaxError: expected expression, got ‘<‘
var defaultBlockWidth=240;</p>
Hoping this could help,
Thanks