We tried some of fthe mods on a test forum and had severe trouble with them. Later found a css-based fix that apparently works. You do need to link to the image using BBC-tag 'img' (image button). Flickr hosting works great and so might other sites do, but not tested in detail yet.
A crude and cumbersome method, not really a fix, is adding the image as an attachment, get the local URL from that, then enclose this URL in the img tags.