I'm trying a couple of different ways to show the "publish_stream" extended permissions dialog. Each time I see a blank dialog with title "Request for Special Permissions" show up for a brief few seconds then disappear. I'm doing some very straight-forward stuff:
<fb:prompt-permission perms="publish_stream">Grant Permission</fb:prompt_permission>
The problem is... I'm an idiot.
The dialog shows this behavior if the user has previously granted this permission. That's why it worked for some permissions, and not for others (that must have been granted through other means). When I revoke the publish_stream permissions for that user, it works.