Items missing from PDF when exporting from Illustrator

[#1]

Hello,

I have created several documents in illustrator, with several art boards and several different items on each art board.

When I export these as a PDF to be able to send across on email or to print out, some of the artwork from each art board is missing. Yet when I open the AI document in illustrator, all of the elements are there.

I've never experienced this before where exporting as PDF from illustrator.

I am using illustrator 2020 & the latest version of Adobe Acrobat Reader DC.

Any help or advice would be greatly appreciated! Many thanks.

[#2]

First confirm that you are actually opening and checking the PDF in Acrobat Reader or Acrobat Pro, not an email or browser app. If so... I recommend you post in the Illustrator forum, with a link to the problem PDF if you are able to share it publicly. Unfortunately, if you aren't able to share it, the chances that the public can help is fairly small.