Ran into a little bit of Flarum (our forum software) weirdness last night. I tried to post a couple of posts to the Show & Tell forum. But instead they went out as PMs to the last user I had PM'd. Apparently once you start a PM, all your messages default to private messaging that same user. 😕
The work-around is, while composing your new message, click on the "2 recipients" button, click each recipient to remove them, and then (important bit) scroll down and click the OK button at the bottom of the overly large modal dialog.
Yes, I'm a bit annoyed with Flarum today. 🙂
We'll look into updating Flarum... hopefully some of these rough edges have been polished off (without adding too many new ones!). But meanwhile, if you find yourself in this situation, now you know how to get out of it!