thumbnails not cropping

Suddenly the thumbnails on homepage (slider and static) are not cropped to the default size. Not sure if this started after the WP 3.9.2 update. I have not changed any thumbnail images nor resized them.
I use child theme and the regenerate thumbnail is installed.
I checked and the alx_setup had proper options:

add_image_size( 'thumb-small', 160, 160, true );
add_image_size( 'thumb-medium', 520, 245, true );
add_image_size( 'thumb-large', 720, 340, true );

I tried to add this to my child functions.php file but didn’t help:

function alx_setup() {
		// Thumbnail sizes
		add_image_size( 'thumb-small', 160, 160, true );
		add_image_size( 'thumb-medium', 520, 245, true );
		add_image_size( 'thumb-large', 720, 340, true );

	}

With each image of different sizes, home page looks pretty bad with uneven thumbnails.
Any help to fix this?
Thanks.