I am seeing the same behavior but only when changing themes (which I need to do). If I use my original Twenty Twelve theme then when clicking on thumbnail I am taken to a slideshow and not to direct image. If I change to a different theme then clicking on thumbnail takes me to direct link of image.
I have deactivated most of my plugins (not SEO etc) which made no difference.
I also deactivated and deleted the Google Plus Express plugin and re-installed but this didn’t help either.
Thanks for looking into this.
Colin
