Using the Jetpack gallery with the Customizr theme
The Customizr theme uses it's own gallery design, which includes a lightbox navigation when clicking on an image.
If you have the Jetpack plugin installed and you want to use the Jetpack built-in gallery, you'll need to disable the Customizr gallery first.
This can be done from the live customizer panel > Main content > Galleries, by unchecking the option.