Missing numbers on footnotes

AndressaSA

New Here ,

I have no clue anymore how to solve it.

The references to footnotes are working fine. The numbers are appearing and leading to the footnote. But when I put the epub in the app the numbers on the footnote are not showing. So the person can't go back to the text once she clicks to go to the footnote reference.

What can I do to make the numbers on footnote appear again?

Following a example on Thorium.