I’m not sure if this is what is happening to you, but my experience is that photos are not uploaded until they are actually posted to the forum. In other words, you can’t see the photo while you are composing your post or when you preview it, only after you click the “post” button. I wish it wasn’t that way, because sometimes I’ve had to go back and edit after posting, for example, when the photo comes up sideways, and would rather do my editing in the background, but that’s the way it is.