Interactive features don't or rarely work

"how do you make a document universally accessible, especially outside an idealized reader platform..."

No such type of document exists, so there is no answer.

"PDF is supposed to be a universal format, and for some vast percentage of the user base, it only gets partway there. It was once there, but the dilution and corruption of the installed reader base"

PDF was never supposed to be universal, it's portable (PDF: Portable Document Format).
The only time it could be considered universal by some was in the 90s, when Adobe Acrobat Reader was the default PDF reader pre-installed on all Macs, all PCs/Windows and when mobile devices didn't exist.

"I fail to see how putting a PDF in a PDF portfolio solves any of the problems with a vast, even greatly majority installation of third-party, second-rate readers and a gulf of misunderstanding on the point by some majority of PDF audience."

Create a PDF Portfolio and try to open it with a program other than Acrobat (or Foxit), and you'll understand right away.

"James Gifford—NitroPress There is nothing you can do about this. There is nothing (realistic) Adobe can do about it. You can only work around the many limitations of what end-point reader your audience is likely to use, and limit the features to what that reader supports..."

This is not true, Adobe reacted a long time ago.

The easiest way is to place your interactive PDF in a PDF Portfolio.
Otherwise you can use these great tips (copy-paste the URLs in Google Translate if you can't read French):
https://www.abracadabrapdf.net/ressources-et-tutos/js-et-formulaires-ressources/forcer-utilisation-pdf-avec-un-vrai-pdf-reader
https://www.abracadabrapdf.net/ressources-et-tutos/js-et-formulaires-ressources/forcer-utilisation-pdf-avec-acrobat

Hi @Viktoria24203226e6hj:

It's a very frustrating situation:

1. Some of InDesign's interactive features were designed to be used with Flash which reached end of life at the end of 2020.
2. Some of InDesign's interactive features work well in Publish Online or a fixed layout ePub, but are not supported in PDFs.
3. Some interactive features work as expected in Adobe Acrobat and Adobe Acrobat Reader but not in 3rd party PDF readers.
   • We can't blame Adobe for that: the 3rd party reader companies are in charge of how compatible they want to be with PDF standards. @Dave Creamer of IDEAS mentioned two examples, there are plenty more.
   • It's also hard to control random people accessing our files who want to decide how they read a PDF and have no idea about the lack of compatibility that some of the readers deliver. You might test this theory by asking "those it works for and those it doesn't" what applications they are using to access your files. 

Admitedly, the post below is meant as a sales tool to help promote in5 from Ajar Productions (by all accounts an amazing product but not one that I use) but it also offers a useful list of what does and doesn't work using Publish Online, fixed layout ePubs and then using their product to export to HTML5, while simultaneously acknowledging the limitation of trying to create a reliable interactive PDF.

https://ajarproductions.com/blog/2018/03/26/interactive-pdf-is-dead-heres-what-you-can-create-from-indesign-thats-even-better/.

This is another sales tool (sorry!) but it offers another look at the same dilemma. 

https://www.maglr.com/blog/digital-publishing-and-the-end-of-the-interactive-pdf

The bottom line is an interactive PDF is probably not going to be way to go for you. You might want to take a look at Publish Online, which is included within Adobe InDesign or HTML5.

FWIW, I created and continue to maintain an InDesign to interactive PDF that I use when teaching and it works great, but I know the limitations, I work within the limitations and use Acrobat or Acrobat Reader to display it to my students as we work through each class. It's a very controlled environment. 

~Barb

Are you or the PDF users using either Acrobat Pro or Acrobat Reader?

Windows used the Edge browser by default; Mac uses Preview. I would next expect either of those to work properly. 

If using an Acrobat product, the following should work:

• Zoom should work but I would use Go To Page View in Acrobat--it remembers the zoom level too.
• Next/Previous buttons should work.
• Be sure you are copying the entire hyperlink from a browser to paste in; browsers don't show the entire link by default, but if you click on them, it will. Don't type it in.
• For linking within the document, either text or page, use Go To Page View instead.
• Use a TOC for hyperlinked bookmarks. 
• What animation did you use? They don't work in a PDF. 

Finally, how did you export the PDF?

One thing I find to be consistently misunderstood is that interactivity is dependent on the host platform and format... not on the tools used to create it. You can build interactive and multimedia elements in a dozen ways, but in the end you have to export to (1) a document format that supports them that is then (2) opened and read in a reader/viewer/platform that supports those features.

The combination, especially (2), is just not as common as most seem to believe. While interactive "pages" surround us, most are part of full-featured apps, or docs tailored to a particular underlying platform or reader. There are very, very few options for creating a standalone document that can be circulated and put on its razzle-dazzle show for all, or even most readers. PDF is not one of them. Neither is EPUB.

In what format do you export your documents?
Whether PDF, ePUB or HTML, the way interactivity works depends on the software used to read the document, not on the platform or the document itself.