The file is designed where certain graphic elements are grouped together to make editing easier for others. In this case, horizontal dividers are made from two basic rectangles and a text box, grouped together.

Each rectangle shape is tagged as "horizontal divider" in the export options for accessibility. When I export to PDF and run the full accessibility check, I'm told that the group failed the "figures alternate text" test.

I then apply alternate text to the group in the export options. I run the full accessibility check in Acrobat and I am told that everything inside the group failed the "nested alternate text" test.

I remove the alternate text from the rectangles, export, run the full accessibility test, and I'm told the rectangles failed the "figures alternate text" test.

The bug is that no matter how the file is set up, it can't pass the full accessibility test. If I include the alt text, I get an error that alt text is nested and that I need to remove the alt text. When I remove the alt text, I get an error saying that alt text is needed. I either get one error or the other.

While this could be fixed in Acrobat if it were a one or two page document, these horizontal rules exist across hundreds of pages and there should be a way to set it up in InDesign so that they export with the correct alternate text applied to them so it passes the accessibility full check.