well, when i tried it the day before yesterday, it was with level 1, and it grudgingly allowed me to jump the ledges (maybe 1 in 5 times)
but when i tried it yesterday, it was at level 5 - which should have been more than enough, space wise - but it refused entirely to do it
also i tried jumping past a few terrain obstacles, small things like cactus, and it didn't allow that either (this was trying to jump like... 3-4 squares away with a max range of 15 squares)