I don't think it's so much a bug, as just tricky to get past that point.
I'm not sure, but from what I remember (I haven't played in a long time now), I got stuck there too for a bit. I was running up the wall, then jumping. It didn't work.
It seems logical to do it that way, but you have to do the opposite. Jump first, then run. After jumping most of the way and then running the rest, Anon will automatically grab on to the edge and pull himself up.