Glitch with Corner Pin

Hello, looking for help! 

So I'm using the Corner Pin effect to create the look of a "door opening", applied to a black rectangular PNG. I set my key frames at the proper start and stop points. However, in the final 4-5 frames of the animation, the motion jumps to the end position, and then jumps back to where it was. Essentially creating the effect that the door opened, then slightly shut again, then repoened. 

I've rendered the effects and exported the clip, and this glitch still remains. There's no leftover or weird keyframes in place or anything. 

Attached is the final export video, showing the glitch. And also the screenshots of my workspace, showing that there's no keyframes in place that should be leading to this jump.