i don't think jumping the string is the issue.it's ducking the string that is.by the time that deer heres the noise and starts to duck that arrow is on its way. And once he gets his feet under him that arrow will hit high or go over then the deer jumps.so if you shoot low you plain just missed.There is another angle here that has happened to me deer just don't duck they turn at the same time 20 years ago i shot at a dor quartering away from me 7 YARDS this deer ducked and at the same time turned away from the noise i seen the arrow miss 235fps i seen it they can do it.There also are the unexplain entry and exit holes when your shooting down from a treestand one would think the hole on the side you shot would be higher than the exit hole. I have seen the opposite because the deer was ducking and turning away from the sound by turning i have seen deer almost laying on there side to get away from the noise

you can use your pepper spray my 12 gauge with 3 inch slugs works fine