Okay, so I was exping in the mire earlier today and somehow my PPA fired off with Unlimited Shot active. Here's the play by play first, then the log:
Unlimited Shot loaded with Patriarch Protector Arrow
Barrage(just wait)
Sharpshot
Sidewinder
Arrow is gone and I had to reequip
Barrage WEARS OFF
Demon arrow fire and attack down proc
Now I know barrage and unlimited shot don't stack but I didn't even use it(see the log). The ONLY shot I fired was the Sidewinder, which had the Unlimited Shot PPA attached to it so why didn't it work?
I called a GM and they're going to investigate but it doesn't make sense that I would lose the arrow. Screencap below:
http://img.photobucket.com/albums/v4...mic/WTFPPA.jpg
tl;dr
XI Wiki

