Are you talking about the Wagtail userbar not appearing? I happened to finally get curious enough about this literally just a few days ago. It was happening for me on sites after I switched them over to using SSL. The JavaScript that injects the userbar wasn't using the correct protocol scheme to load the stylesheet, and the browser was refusing to load insecure resources (http) when the connection was made over https (reporting 0 bytes is typical in this scenario if I recall correctly). If you don't have SSL involved, then this may not apply, although I suppose this might happen across different origins, too, if you have Content Source Restrictions in place. I haven't gotten around to filing a bug or submitting a pull request for this, but in short you need to:1) make sure that request.is_secure returns True. This is doesn't work as expected if you are using nginx or something else for SSL termination, you need to pass a header through and tell Django to look for it when getting the value of request.is_secure. (Google should turn up results on how to do this). You can tell if this is an issue if you visit your page on https and bring up the JavaScript console. If the value of wagtail.userbar.origin is "http://example.com" and you are visiting "https://example.com", then you are getting the wrong value for request.is_secure2) modify or override wagtailadmin/templates/wagtailadmin/userbar/frame.html -- with the change above, it should be the case that wagtail.userbar.origin is set correctly, but it doesn't seem to be used in line 12. If I replace line 12 with:u.src = wagtail.userbar.origin + '/{% static "wagtailadmin/js/userbar_embed.js" %}';
... then the userbar appears as expected. Anyway, I think that was the intention for that line of code. There might be a way to do this with a protocol relative URL, which would be simpler, but the browser didn't seem to like it, and I only spent a few minutes on it.
SECURE_PROXY_SSL_HEADER = ('HTTP_X_FORWARDED_PROTO', 'https')