Some images are not being optimized.

Hi,

I’m getting some images that are not optimized here:

WARNING – (144.6 KB, compressed = 115.6 KB – savings of 28.9 KB) – http://d3uv72d4ga7dsx.cloudfront.net/wp-content/uploads/2015/11/Cover.jpg
WARNING – (47.1 KB, compressed = 32.7 KB – savings of 14.4 KB) – http://d3uv72d4ga7dsx.cloudfront.net/wp-content/uploads/2015/11/Cover-830×400.jpg
WARNING – (28.5 KB, compressed = 20.0 KB – savings of 8.5 KB) – http://d3uv72d4ga7dsx.cloudfront.net/wp-content/uploads/2015/11/Cover-500×300.jpg

and:
302.0 KB of a possible 446.6 KB (68%) were from progressive JPEG images
FAILED (144.6 KB) – http://d3uv72d4ga7dsx.cloudfront.net/wp-content/uploads/2015/11/Cover.jpg

Any ideas?
Thanks,

debug info:

Array
(
    [width] => 1500
    [height] => 1000
    [file] => 2015/11/Cover.jpg
    [sizes] => Array
        (
            [thumbnail] => Array
                (
                    [file] => Cover-150x150.jpg
                    [width] => 150
                    [height] => 150
                    [mime-type] => image/jpeg
                    [ewww_image_optimizer] => No savings
                )
            [medium] => Array
                (
                    [file] => Cover-300x200.jpg
                    [width] => 300
                    [height] => 200
                    [mime-type] => image/jpeg
                    [ewww_image_optimizer] => No savings
                )
            [large] => Array
                (
                    [file] => Cover-1024x683.jpg
                    [width] => 1024
                    [height] => 683
                    [mime-type] => image/jpeg
                    [ewww_image_optimizer] => No savings
                )
            [custom-size] => Array
                (
                    [file] => Cover-500x500.jpg
                    [width] => 500
                    [height] => 500
                    [mime-type] => image/jpeg
                    [ewww_image_optimizer] => No savings
                )
            [custom-size1] => Array
                (
                    [file] => Cover-500x300.jpg
                    [width] => 500
                    [height] => 300
                    [mime-type] => image/jpeg
                    [ewww_image_optimizer] => No savings
                )
            [custom-size2] => Array
                (
                    [file] => Cover-830x400.jpg
                    [width] => 830
                    [height] => 400
                    [mime-type] => image/jpeg
                    [ewww_image_optimizer] => No savings
                )
        )
    [image_meta] => Array
        (
            [aperture] => 0
            [credit] =>
            [camera] =>
            [caption] =>
            [created_timestamp] => 0
            [copyright] =>
            [focal_length] => 0
            [iso] => 0
            [shutter_speed] => 0
            [title] =>
            [orientation] => 0
            [resized_images] => Array
                (
                    [0] => 1900x700_c
                )
        )
    [ewww_image_optimizer] => No savings
)

https://wordpress.org/plugins/ewww-image-optimizer/