Problem with image in compiled ePub

Hi Scrivener community.

I’m having a problem compiling an ePub of a book that I originally published in 2021. I recently updated the book’s backmatter, and am now getting the blue question mark inside the box where an image should appear—but only in the book’s last chapter, and on the backmatter page I updated. The image is showing up just fine in other parts of the compiled epub.

When I run the file through an ePub validator, I get two error messages:

"Error while parsing file: Duplicate ID “bluebell rule”
AND
“Referenced resource could not be found in the EPUB”

Which is weird, because as I mentioned above, the referenced image shows up just fine in other chapters…

I tried zapping gremlins on both pages, but that didn’t seem to help.

Any thoughts on what might be going wrong, and/or how to fix this?

Thanks!
Jackie