However, at some point in the last couple of months it stopped working for me; I get the error code bX-m9h15s when trying to authenticate. As far as I know, my OpenID server is working just fine (OpenID Checkup agrees).

If I use my server URL directly (instead of an HTML resource that uses delegation) it works, albeit without incorporating any of the Simple Registration data. There are plenty of other reports, but nobody competent (and/or employed by google) has responded.

There doesn’t seem to be a true bug reporting facility for blogger; the competent users help the incompetent users on the discussion forum, but I can’t see any developer or even QC presence there.