Featured Image Problem

Hello! I used your free theme and then saw how awesome it was so upgraded to Pro. It's been working great until recently. My problem is this: Whenever I set a featured image for a page (in the correct 1140x450 size), it resizes to a big square and only shows part of the image. It's very strange and won't even show up in slider. I've checked the edit photo and everything says it's the correct size. Please help! Thank you