Images suddenly showing up as attchments

[Exeter]

I use the WYSIWYG editor.
Both the simple and complex one fail in both FF and Chrome.
I voted for one one the issues, but they don't seem to be exactly the issue I am having.

I'll try some trouble shooting with the source editor once I renable it.

A curious detail:
After adding an image it appears as an attachment "[attachment]123[attachment]" in the body of the WYSIWYG editor.

I can then add the attachment using the drop-down of the attachment icon. This adds and displays the image properly in the editor. The image management dialog pops up as expected.

When I save the post, the images all revert to attachments (simple links). showthread.php displays no images. Edit that post again, and I see images in the editor just like I did when I saved the post.