Video won't export in horizontal format, works fine in vertical

So I'm editing a video that was shot vertically, but I zoomed in to make it fit a horizontal format.
When I export the vertical version, it exports without issue. But the horizontal one, for some reason, just isn't working and I have no idea why.  It'll get to the end of the export, and then it'll say it can't be played due to unsupported encoding settings.

I'm using Premiere 2025 on a PC. I think the footage was shot with an iPhone, but I'm not sure.
For what it's worth: the footage is showing up fine in the preview for the vertical. When I moved it to a new save file for the horizontal it looked really over-exposed, but I think I fixed that in the lumetri color settings.