As shared above, that this is happening with the latest version of the Adobe Reader DC on the latest OS High Sierra. So could you please confirm whether its started happening immediate after updating to the latest version or you had this problem earlier too?
Also, have you tested with any other document? If not then please do.
Try to Reset Preferences of application as suggested in help document. How to reset Acrobat Preference settings to default. (updated link)
For Reader DC you may try- close Acrobat Reader and delete ~/Library/Preferences/com.adobe.Reader.plist
With the latest version on High Sierra this issue has not been reported yet. However if you have experienced this then we need to check it at our end.
Let us know the update on this, if it still doesn't fix.
Thanks for your response. I installed the Reader after I'd already updated my OS to High Sierra—so I can't speak to its behavior prior to the High Sierra update.
I have tried this on multiple PDFs and I get the same result each time after annotating and saving, the PDF file loses its finder tag.
There is no "Repair Installation" under Help in my version of Adobe Acrobat Reader DC. Having just updated Reader DC again (2018.009.20044), the problem still persists.
I apologize for the delay in response to your query.
As you have just mentioned about the latest update, even after installing the latest update its still not working.
Not the repair installation, try reset preferences as updated in the above reply. And see if that makes any difference and if it doesn't then
Would it be possible to share a sample document with us?
"You can share the file with us via email. And you can send it to the email that is shared via private message. Please do mention your forum thread in the subject"
An update on the situation: apparently, one thing that activates the bug is remove/delete a highlight and save. In other words, last I checked (10 min ago) the tags were still there after a mere highlighting and saving. But once I remove a highlight and save, my finder tags vanish right away!
Finally, I think I sent you (or someone) an email, but so far no reply. Please let me know again how I can send you a sample pdf (but FYI, the pdfs I use are standard academic articles, nothing fancy; I've tested quite a few pdfs, all with the same result). I'm currently running the latest version (18.11.20038.267465), yet the issue persists: please do something about this very annoying bug!