I'm not sure why this is happening, but it's persisted for months. Often all but a few message notifications are broken and one of these three scenarios usually happen: the notifications don't show at all, they say "left a message on 's wall", or they actually show up the way they should. For me, this happens on all browsers I've tried, Vivaldi on Windows, Chrome on Windows and Android, Firefox on Windows and Ubuntu (specifically 16.04), Microsoft Edge (Windows exclusive) and Amazon Silk (on Fire OS). My discussion notifications (the one with the bell) are fine, it's just the one with the speech bubble that's been broken. If anybody could give a possible solution I will gladly thank them.