Alright, I figured out the issue. My combat system moves whoever gets hit slightly backward with body velocity, and then if it’s the last hit it calls the function in the module to knock them back. This causes the body velocity added by the knockback function to be overridden by the one that pushes them back slightly, causing it not to work. When I cut the body velocity and pasted it back, the old one had already been deleted so it then works.
Thanks to everyone who helped, I appreciate it a lot.