Text formatting can break backlinking endnote texts to endnote refs when exported to PDF (Print)
to explain the issue:
Sometimes backling from endnote text to endnote reference number will not work.
To make it work at all I found the following minimum requirements for PDF export:
PDF Export (Print)
Compatibility: Acrobat 5 (PDF 1.4)
[x] Create Tagged PDF
[x] Hyperlinks enabled
Even with that sometimes only linking from the endnote reference number to the endnote text will work, but not backlinking from the endnote number in the endnote text to the reference in the main text.
What I found:
If you want linking back from the endnote number at the start of the endnote text you have to be careful with formatting of that endnote number which in fact is a special character.
The endnote is using a paragraph style without any specialities. No overrides, no character styles applied:
RESULT: No issue with linking back and forth between endnote reference number and number in the endnote text.
Now I had the idea to format that special character, the number that starts the endnote text with a character style.
RESULT: Linking from the endnote reference number to the endnote text worked. BACKLINKING DID NOT WORK.
MORE DETAILS IN THIS THREAD:
Endnotes not exporting with links to PDF
Mr_Wonderstuff, Nov 18, 2020
WHAT BROKE THE BACKLINKING:
 Character style applied through a GREP Style
 Character style applied directly as formatting
 Properties directly applied as overrides without a character style
WHAT FINALLY WORKED:
 Character style applied as nested style through the applied paragraph style:
Character style to 1 tabulator character
I did not test on to eliminate other factors.
Maybe one of the used properties are the real culprit?
What I defined in that character style and also tried to apply as character override was:
Character width and height: 70%
Baseline Offset: 2 Pt
Fill Color: "C=100 M=0 Y=0 K=0"
( ACP )
All InDesign 2021 test documents and the exported PDFs. Also the used joboptions-file can be downloaded from my Dropbox account:
Thanks for reporting the issue of backlinking not working for Endnotes with WR Composers.
We’re going to review this shortly.
Adobe InDesign team
Hey all, Christine's solution did the trick:
Convert the endnotes to footnotes, and then back to endnotes and you'll see immediately the endnote reference numbers at the back will now be live links to their place in the text. It works!
Roope Koski commented
The fix from Anonymous worked for me. I switched back from World Ready Paragraph Composer to Paragraph Composer in my endnote style, and links back from endnotes to reference started working in exported PDFs.
Uwe Laubender's idea of using a nested character style sometimes worked too, but not consistently.
I had this issue of it not back-linking as well because I had a character style for the endnotes. What I found that worked was Convert the Endnotes to Footnotes, then do it again and Convert Footnotes back to Endnotes, and it linked for me when I exported the epub. I've spent too much time trying to figure this out as well, so I hope this was able to help someone!
Uwe Laubender commented
my bug report is NOT about the World Ready Paragraph Composer. You'll see that with my linked sample documents. That the World Ready Paragraph Composer can be an extra issue is out of question.
( ACP )
I use endnotes in many publications, and have never succeeded in getting backlinking (linking from endnote to reference in text) to work. Clients request it regularly, and I have to tell them it's something InDesign simply cannot do.
My endnotes are in an unmodified paragraph style, with no character style or character formatting or overrides of any kind.
I created a PDF from Uwe's InDesign file using my own joboptions, and that PDF has backlinking. But PDFs I create from my own files do not. This tells me my joboptions are not the issue.
I copied a paragraph from Uwe's InDesign file, with its accompanying note, into my file and made a PDF. Backlinking worked for his text, but not for my existing text. This tells me the problem is somewhere in my text formatting.
One aspect at a time, I changed Uwe's paragraph style to match mine, creating a PDF each time, figuring the place where it broke would tell me which aspect of my own stylesheets is breaking backlinking.
Long story short: having the endnotes using the WORLD-READY PARAGRAPH COMPOSER breaks backlinking. As soon as my endnotes were formatted using the regular Adobe Paragraph Composer, bam, the backlinks function perfectly.
I could not be more satisfied yet angry.
I am a newbie to INDD so is it possible for you to tell me in simple steps how to fix this issue? I have 5 books I need to fix, maybe a total of about 1500 endnotes. Thanks.
I have encountered the same sorts of problems with endnotes not backlining in pdf exports. I have also found that when manual backlinks are inserted in the endnote page, this causes a program crash when trying to export to EPUB. Still not fixed in latest 2021 version.
I have reported the bug and also a feature request for the ability to export back-linked endnotes to pdf.
This would save me loads of time!
Uwe Laubender commented
Now tested this also with:
InDesign 2020 version 220.127.116.112
InDesign 2019 version 18.104.22.1683
InDesign 2018 version 22.214.171.124
Exact same behavior.
( ACP )