Forces don't work after I move keyframes

I have a very basic animation set up with a cell fractured UV sphere and a force field. I have scaled the sphere to 49.5 and the force strength has 3 keyframes, one at 0 strength, the second a frame later at 150,000 strength and the third 75 frames later at -150,000. The animation works perfectly fine when it starts at frame one but this is for another animation where it is supposed to start at frame 850. So when I move the force strength=0 keyframe to frame 850 nothing happens. (I also have gravity turned off). Any help would be greatly appreciated as this is for school project. If i haven’t been clear on my problem ask me some questions and I’d be happy to clarify as this is my first time posting to this website.