A PDF generated by Microsoft PowerPoint 2019 has metadata, anonymized below:
Google Chrome and FireFox PDF.js, evince readers and even
exiftool will display the keywords in the document properties. But not Acrobat Reader, why?
exiftool, run with
-a shows no duplicates for
Keywords however this metadata is stored in different places inside the PDF.
The PDF Reference, version 1.7 (version of this PDF file) includes this metadata among others, although it is not specified whether or not the list should be separated by semicolons. Also, using only one keyword to isolate the problem does not change anything.
Question and paraphrased answer posted in the Adobe Support Community, with a link to the source.