The following compatibility issue has been found in Expression 1.2.3 with WordPress 3.9 – clicking on the fullscreen button of the Full-width slideshow page makes the first image always displayed on the slideshow regardless of the currently selected image.
We have released an update with a fix – version 1.3.0. If you have version 1.2.3 or older installed, please update to the latest version in order to fix this compatibility issue. You can either use the theme’s automatic update functionality to install the update or you can download the update from the Downloads section of your ThemeForest profile. You can read more about how to update the theme in the “Updates” section of the documentation.