I used to have the same problem with a short but high jump in de_52villabacho, SoUlFaThEr. You know what solved it? I removed the jump and just replaced it with a normal 2-way connection. Worked 100% afterwards. I KNOW, I KNOW - those 2-way connections are ugly, bots bump into the wall first, etc. etc. But in rare cases, when they are so close to a wall that they touch it with the tips of their noses anyway, it can be a clean solution. If it doesn't work first, try placing the upper WP a tad further away from the edge - although it may hurt you to have a simple, ugly old 2-way connection up somewhere. But ppl will never see it, and if it works, so what?