I'm using Unity 2019.4.24f1. I have a simple animation of 2 sprites. 1 for 2 frames, then the other for 2 frames. At a sample rate of 12 the animation plays perfectly, only too fast. If I lower the sample rate to 6, then the animation doesn't play. At 8 it plays once and then stops. If I keep the sample rate at 12 and double the amount of frames each sprite should be shown, I get the same result: no animation. I can't figure out how to get those two sprites to switch slowly using the animation system in Unity.
EDIT: Here's what it looks like. I changed the keyframes and that changed the values for the different things the system does, but the results are the same.