I'm trying to create a simple river stream by manipulating UVs. I added an AnimationPlayer to my river plane, added to it the Property track and specified material/0. I set the UVs to 0, 0 and tell AnimationPlayer to add a key frame at frame 0. I move to 1 second and change the UVs, then set a keyframe. Nothing happens, the animation is not saved. I'm sure that I'm missing something, but what is it?