Twitter needs image in Post Cover

Seems that unless you manually set a post cover in the blog editor, twitter will not pick up an image when you share a blog post. Does not matter that the settings says "first image as post cover".
http://www.awesomescreenshot.com/image/2440697/c4881f6e0ef2d1f63a304f1ebde0b07f

If this is a bug maybe you could fix it for the next release, as not all our bloggers uses the "post cover" button.

Cheers