table of content useless after "reflow PDF" - every headline is on page 1

[hklene]

On applying the "reflow" to a PDF, the progress bar and display of the pages work fine.

Only the table of contents is messed up, as it shows all entries on page 1

https://librera.mobi/faq/convert-pdf-to-epub/

Closing and opening the saved epub-version doesn't help realigning the contents.

[hklene]