ok i tried somehting new, maybe it`s an error in the theme..
my folder strukture is intern/16subfolders/and in each subfolders several other subfolders and in this folders are the pictures around 2,8k.
If i put 5 subfolders under /intern i can arrange the order of the folders perfectly..if i put more subfolders in this structure it doesn`t load anymore. if you want i can give you access to it and you can try it out by yourself.