Used to be that when I visited a profile, hit Message, and sent it, I'd get taken straight to the PM page. That's not happening and it's definitely a bug (according to Wrecked Avent's first reply here).
This happens whether I've got an active PM going, no PMs going, or even if the person has me on ignore (someone did that to me for testing purposes, I'm not a bad person I promise!). I send a message, and then their profile page just refreshes. In the case of ignores, I don't even get an error message or anything!
The PM does get sent, and the conversation does get created (if it needs to be). Except when, y'know, they have me on ignore.