Sometimes your try hard to be able to jump higher but you just cannot seem to make any progress. You try all the different ways to train, maybe make some progress then you fall back never seeming to really do any good. Maybe you are over trained and burned out or maybe you need to focus really good on your goal and stop trying all the different things you have been doing.
How about making your vertical training as simple as possible for a while and see what happens. Get rid of the fancy workouts and do some simple things. Reduce the number of days you workout each week and work harder on the days you do workout. This may give your body more time to rebuild itself so it can grow and prepare you for the next workout.
Don’t make it complicated, keep it simple. You might do squats one day and take the next day off. The next workout might be just jumping as high as you can until your jump gets sloppy, take the next day off. You may be able to come up with something like that which may work for you, try it for a few weeks or a month and see if there is any progress.
Do some upper body workouts if you do not normally do that. Try bench press and pull-ups, a stronger upper body will help out a lot. Work out your mid section, a stronger mid section will help keep your spine stabilized. Every time you move, your abs and lower back come into play. Keep it simple and see how you do.