Johannes,
Thank you for taking the time to contact us. We were able to track down what is going on with the gallery shortcode. Here is a link to a zip file that will correct the problem. There are two files in the zip file, gallery-shortcode.php and photo.php. You’ll have to replace the existing files with these new files.
gallery-shortcode.php goes in the /intense/shortcodes/gallery/ folder
photo.php goes in the /intense/templates/gallery/effeckt/ folder
Once you replace these two files with the ones I have included in the zip file, the effects should work correctly.
Let us know if you still have issues.
Thanks,
Josh