I have impending victory talent chosen and when I save the macro with impending victory it changes back to victory rush. It also doesnt appear to be getting kicked off with victory rush in the macro

The saving with Victory rush is what it is supposed to do. As for the second part this will be for other factors interfering. If the conditions for Impending Victory are active and you type /cast Victory Rush in your chat box you will see that Impending Victory is executed.