Some images in a document appear as a link icon.

Recently, I noticed that some (not all) images in documents appear as a link icon, but I’m reasonably sure they were just dragged in from somewhere (likely, from the Research folder). Also, on the Mac side, the images appear just as images, not as links or icons. So I’m wondering if there’s a way on the Mac (v3) to tell if a file is going to show in iOS Scrivenr like the icon, or like the image? Note that other documents in the same project display their images correctly.

Are there image types that aren’t supported in iOS Scrivener’s RTF implementation?