Problem multiavchd/imgburn changing aspect ratio

Howdy,

I have encountered a problem that is probably easily solved and will probably make me look really stupid, but here goes anyway.

A little background. I got a movie on Blu-ray whose picture is inexplicably stretched horizontally. I was able to reframe it in Handbrake to correct the image. I changed the dimensions to 1724×1080 for a 1.66 frame (I know--those numbers don't seem accurate, but taking into account the original 1.85 AR, black bars, 1080 resolution, etc. etc, and some math, believe me, it's right.) I know the picture now looks correct because of multiple wasted discs confirming it. They're wasted because, while I was able to burn the video to BD-R, they didn't have autoplay or chapters. Which brings us to...

The problem is this. I'm now using multiavchd to encode an avchd and burn it using imgburn and get a disc with my autoplay and chapters. The height and width are in the program correctly, at 1724×1080, but when I create the project, the resulting image disc is exactly the same as the original BD (stretched all the way to the sides) rather than in the framing I made. I don't now if this is multiavchd or imgburn (but my initial test runs were with imgburn and the ratio was correct).

Like I said, probably an easy fix.

Help!

Thanks in advance!