Hard Crop Fails on Big Image sizes.

Hi guys!

Hard crop works when I’m cropping to small image sizes like this:
add_image_size( 'thumb-standard', 150, 150, true );

But hard cropping fails when I’m cropping to larger images like this:
add_image_size( 'thumb-slider', 1264,?927, true );

Is this a problem someone is familiar with?

I have already tried to regenerate my thumbnails (twice).

Best regards
Lasse