I just encountered a very odd bug where Force Barrier would fail to activate on my Defender. I would get the disintegration affect when hitting enemies with a charged melee but I would not get the overshield. I recorded a short [url=https://dl.dropboxusercontent.com/u/293710/NoForceBarrier.mp4]gameplay clip[/url], but this odd bug had been going on for a few minutes before that. It seemed to reset when I died. I think it was probably only in that area but I can't be certain. Wish I could give more information, hope this helps!