Thickbox module not loading all images
Thickbox -- nothing to do with Drupal -- is no longer supported. I highly recomend using Colorbox. (On Drupal)

(edit) The problem doesn't have anything to do with a modal image viewer. I inspected the code to find the URL of each image and they don't work. Chances are that the images are not being uploaded complete because of an upload limit or they are too large for image cache to successfully manipulate.

In php.ini make sure that:  

max_execution_time to around 120 and
realpath_cache_size to 512K, 1M or even 2M.
max_input_time to around 120.
post_max_size = 12M to 16M (or large enough for your images)
upload_max_filesize = 12M to 16M (or large enough for your images)


In the content type widget configuration make sure that Upload Max size is set accordingly.