Can't play MP4 in UE5 Sequencer

I’ve tried posting the MP4 in raw, using the media player/media texture/file media source methods, etc. For whatever reason, the MP4 won’t play. My sequence is a simple in-game camera sweep with some audio, then I want to load up an MP4 cutscene that couldn’t be made in-game. I can put them both on the same sequencer timeline but the video won’t play!

I have the electra plugin activated, nonstandard codecs checked in project settings, switched RHI to default, etc. Can’t figure out what’s wrong.

The video is less than 10mb, is 1080p, 30FPS. It’ll play in the media player / preview properly, but it won’t play in the sequencer.