Comment 1 for bug 1757583

I further investigated this problem. My initial report was based on annotations to a document sent by a bank. Some forums report that document DRM properties affect the ability to create/edit annotation. See:

https://unix.stackexchange.com/questions/278874/newer-version-of-okular-can-no-longer-annotate-certain-pdf-files
https://bugs.kde.org/show_bug.cgi?id=341999

I was always able to annotate the bank PDF. I just couldn't embed the annotations by using File > Save As...

When I tested again with a PDF I generated from LibreOffice, I found that annotations were successfully embedded using File > Save As...

I used another computer with the same OS and Okular version to replicate these tests for both the LibreOffice and bank PDFs, and the results were the same.

I also replicated these tests on the first computer after changing the DRM setting in Okular (I went to Settings > Configure Okular > General Tab, unchecked "Obey DRM Limitations", and restarted the computer). The results were the same.

I conclude that failure to embed annotations using "File > Save As..." is LIKELY related to DRM but isn't affected by the setting for "Obey DRM Limitations".

My revised recommendation: investigate the annotation-saving behaviour to determine whether its DRM-related, and modify Okular to communicate such problems to the user and provide an effective and documented ways of embedding annotations for all PDFs.