Movie clips are not playing

I was making an animation using Animate 2021 and tried to use a movie clip in my animation. However, the clip just isn't playing. Not when I scrub the timeline, not when I play the animation within Animate, and not when I export the animation and watch it. If I go into the editor for the movie clip, it plays just fine, but if I play the larger scene, it just doesn't happen. Is there something extra I have to do to make my movie clips actually animate?