I know a few of us have run into this issue when trying to post images, simply, they won't. Whether you physically copy/paste, or use the "Insert Image" function, the image appears in your message box, but frequently then when you post it, it's empty. If you preview first, that usually lets you know if it will appear or not, but that doesn't actually help anything, it just lets you know in advance if it isn't going to post, so you don't have to post and then remove.
Obviously not a major issue, just curious.