After Effects Glitch: Keyframes not automatically added after altering position/scale etc

After Effects has stopped automatically adding keyframes after I've changed the timeline location and altered a property of a shape. I'll click the stopwatch to add an initial keyframe - which does work - but then nothing is automatically added after that. I'm able to copy and past that keyframe to another point on the timeline but they remain identical no matter how much I alter them individually - so basically no animation happens at all. I've tried uninstalling and reinstalling the program along with emptying the cache. If someone's dealt with this glitch and could shed some light, I'd be super grateful! Thanks!