Same exact thing is happening to me, just as described by Aleksandar. This used to happen to me almost on a quarterly basis on my Lumia 920. I switched over to a Lumia 1020 about 2 months ago and now this issue is happening again. Oddly, the issue used to happen to me on my 920 about a day before an app update for Facebook would be released. The app update always fixed the issue. Sadly, I haven't seen anything about an app update this time around. I will have to give colinkiama's instructions a shot.