Our app shares a custom open graph story that included a 1200x630px preview image. The preview image however always displays as a small square when posted to the Facebook timeline.
As mentioned here, the header of the website I'm linking to already contains og:image and og:image:width and og:image:height. Still the image is cropped and only a square on the left is visible.
Is there any trick to make the image use the full width? User generated images are not the solution to go for because it removes the link from the open graph object and also stores the image in the user's photo albums.
I know that this has to be possible somehow because it works for apps such as Runtastic Results.