More information after a much testing
I worked with the book with the smallest number of footnotes (13). Put all footnotes into a plain text editor and entered them one by one, testing the epub popup notes after each footnote was added.
After three first three footnotes were added the popup footnotes are working on the Ipad. After I add the 4th NONE of the popup foonotes work. It was nothing related to the content of the 4th footnote, becasue the populs do not work when I repeat the first footnote in place of the 4th footnote.
But for a different epub3 book all 64 popup footnotes work with no problem and some of those 64 footnotes are long. The two books use identical footnote styles and settings.
I guess that hardly anyone is using popup footnotes on a regular basis because I not seen any report of problems and there have been no replies here.
I think it’s time to give up on Epub3 for a while? I’ve spent too many hours trying to debug this one.
Jim