I have a PM label called "Glitch" in which I manually put all of the PM from people I don't want to RP with or with whom plotting failed to go anywhere.
I have no rules directing any PM into that label.
I have one new message, which somehow ended up being sorted in "glitch" but when I go an take a look, my most recent PM there dates from March 22nd, 2015 and I remember putting it there. There are no unread messages from what I can see. I haven't done any sorting/labeling in a while so I didn't accidentally put it there.
Any idea how I can get to that new PM?
Edit: I've transferred the content of the Glitch label into my inbox. Here's the result:
(yes, the irony of having a glitch in a label named "Glitch" is not lost on me.)