I've had issues with websites like Academia.edu - when I import the citation or PDF, the metadata is sometimes incomplete. Missing dates, missing text, etc. When I right click the PDF, there is no option to Retrieve PDF metadata - that option simply does not appear in the context menu.
(Please start new threads for new issues — the thread you posted to was about a different issue. I've moved this to a new thread.)
"Retrieve Metadata for PDF" is only an option for standalone PDFs. If the PDF is already a child item, you would need to fix the parent item metadata, save from a better source and drag the PDF onto that, or (if you saved a webpage with bad metadata and it's an academic PDF) drag the PDF out and try metadata retrieval instead. See the documentation for more info.
But note that you generally will get much better quality metadata, and attached PDFs, by saving from publisher sites rather than Academia.edu.
"Retrieve Metadata for PDF" is only an option for standalone PDFs. If the PDF is already a child item, you would need to fix the parent item metadata, save from a better source and drag the PDF onto that, or (if you saved a webpage with bad metadata and it's an academic PDF) drag the PDF out and try metadata retrieval instead. See the documentation for more info.
But note that you generally will get much better quality metadata, and attached PDFs, by saving from publisher sites rather than Academia.edu.
Can you suggest the best quality sources of metadata for use with Zotero? Google scholar, of course. Is Research Rabbit any good?