Playback lags and audio drops with this one clip.

Hi all!

I have one .mp4 clip that causes playback issues. Often there's a few seconds of lag after I hit the spacebar before the clip plays. Sometimes the video stutters. I also get "audio not found" and :"audio disk I/O overload" errors.

Here are some specifics:

This only happens with this clip. All my other projects play fine. All my other clips play fine. So, it's not a hardware issue.

It's not a "too many clips" or "too many effects" issue. It happens when it's just this clip in the sequence.

If I delete the video track, the audio plays just fine. But if I delete the audio, the video still has issues.

It's a 23.976 4K clip, but I've never had issues will other such clips.

If I play the clip in the source monitor, it plays just fine.

So, that leads me to think this is a sequence setting issue, but I don't have a lot of experince with the technical side of things.

My sequence settings are:

Editing Mode: Custom

Timebase: 23.976

Size: 1920x1080 (i have mixed media, so this seemed best. I tried it at 3840x2160 but still had the issue)

Sqwuare pixels

No Fields

Color Space: Rec. 709

Audio Rate: 48000

Preview File Format: QuickTime

Codec: Apple ProRes 422

Any ideas are super helpful. Thank you very much!