How to toggle pose on/off (animation)?

Hi, so I’m trying to have the player character play an animation (checking time on left hand watch), on key press, and hold on the last frame (I unchecked Enable Auto Blend Out in the animation montage editor, to achieve this). Then, on key press again, play from last frame in reverse, back into whatever animation they happen to be playing currently (could be idle or walking etc.).

I figured out how to play layered animations and all that. Playing the montage forward works fine, but when I try to play it in reverse (Play Rate -1, Starting Position 1), it doesn’t play all the way to the start (the hand gets stuck somewhere in the middle in my case).

What’s the proper way to do something like this? Thanks.