jQuery Isotope loading issue

jQuery Isotope loading issue

I am actually trying to build a image gallery with jquery Isotope. I dont know why, but sometimes the gallery works perfectly and sometimes it has some kind of loading issue as you can see in my screenshot.

Source: www.sarahraaber.com



I already added a timer on pageload and the document ready function to the head of my .js file :-/
Any ideas how to workaround that?