ALT tags missing on hover if one image is overlapping another

[jdwyer]

I have a consistent issue with overlapping PDF images that pass the accessibility test. When you hover over them, their ALT tags disappear, and they show only the ALT tag of the background image. But when I run the accessibility checker and check the ALT tags, they are fine. Any idea how to fix this? I work at a university and would love to have this issue resolved for the visually impaired fixed ASAP. Any help would be appreciated.

The image below shows the issue: The ALT tag on the hover shows the background image ALT tag, not the photo in the forefront. And this is consistent.

I am doing something wrong here, but unsure what it is.

[Abambo]

How did you create the PDF?

[jdwyer]

I made the PDF with InDesign 18.2.1.
I might have figured it out. The background image should be an artifact, and once that is set, the images on top are being appropriately read on hover.