In those fixes, they often need a few tries to work. If doing it to one waypoint doesn't work, try another. It can sometimes take 1/2 a dozen tries for me to get it (in the 757), but in the 767, it only takes a few tries normally.

With the 767 trouble, try uninstalling/reinstalling it again to see if that helps. I might take another look at the 767 in Win8.1, see if it works okay for me (although I am sure I tried all Captain Sim products for FSX in Win8.1). :-/