Can anyone help?
If you are hanging off the ledge by your arms, it should work. If you are just standing at the edge, it won't do anything unless there is a ledge above you to grab onto.
You are playing the PC version and hitting the "Space Bar" to jump, correct?
It occurs in the mesa level underground when you have to climb a totem pole to reach a rope to slide across.
I jump across and am hanging by my hands but no matter how hard i push the space bar it wont climb up. I even used to left shift key to hang off to jump back but it wont jump either. Only way to get off the totem pole is to press C to crouch and i drop.
It is climbable cause my teammate (AI) jumped across next to me and climbed up.