Why does my output video file look different than the preview and rendered images?

I’m trying to do a seamless cut in the video editor. In the preview, it looks perfect, but when I export it, it’s obviously very different.
What’s the deal?

I tried to fix it by rendering the two incorrect frames out as images and editing them, but for some reason THOSE turn out exactly like the preview window?

The only video that has a modifier is the one I’m cutting to, a speed modifier where the speed factor is set to 1, and the multiply factor set to 2.

I’m trying to do a seamless cut in the video editor. In the preview, it looks perfect, but when I export it, it’s obviously very different.

In what way ?
What video format are you using and export settings

The timing is just off, and it makes the cut really obvious.

The file format I’m exporting to is H.264, and the encoding format is AVI.

The source media may not be decompressing correctly, try generating a proxy and timecode for the clip OR convert the media to a frame sequence.