Photos not showing in glaery

I have a strange problem – some photos are not showing up in gallery:
https://imageshack.us/photo/my-images/20/k812.png/

Now the funny part – I can attach them, I can use them as post images and post icons. They have the same permisions as the rest of the files.

We did some cleaning in the uploads directory and to lower the amount of photos made by wordpress and our theme we have set the size of miniatur to 0, medium to 0 and large to 0. WordPress is only generating file sizes hardcoded in theme.