That makes sense. After my previous post, I’ve also found that your team have documented this under the help section (Publish limitations - Obsidian Help).
In the meantime, it would be great if Obsidian Publish could implement a temporary workaround, such as adding a link to the original PDF so that it opens the file on separate window, which at least gives us a way to view the highlight.
Ideally, it would be even better to load the page where the highlight is located. The best option would be to display an image or a zoomed-in view of the highlighted area.