Replaced image not updating in published files

After replacing an image in a Fla file and publishing, the old image appears in the html, except scaled to fit the size of the original image.

I created a 300x600 web banner, then replaced the cta image with one that was 300x250 (images were double sized, then scaled to fit), but it still exports the old image, squashed to fit the new size.

Resetting publish settings, published templates to default, and exporting a spritesheet/texture or separate images doesn't solve the issue, neither does trying Animate CC 2022 and 2023, on different Macs, which I think rules out some sort of cache issue.

Copying the image from the stage to a new Fla file, and publishing that does work, and it appears fine.

File and published example is up here:

https://www.dropbox.com/sh/dqxd15cf2vyd4ue/AABzHlFj59gL_4m2g8YmyfJba?dl=0

This forum is giving me an error when uploading a .fla ("The attachment's test.fla content type (application/octet-stream) does not match its file extension and has been removed.")