If I specify a Default Image URL, that image is always being used, regardless of whether or not there is an image in the content even when "Force Fallback Image as Default" is not checked. The reason seems to be that it generates the following code:
<meta property="og:image" content="the-content-image.png"> <meta property="og:image" content="the-default-image.png">
Since the default image is second, that is the image Facebook uses. Please fix.