Searching portfolio and attachments in Acrobat Pro XI doesn't find file types .docx or .xlsx
I'm using Acrobat Pro XI. When searching in both portfolios and attached documents, the search doesn't find results I know are there.
One of the issues seems to be the file type. I have a Word (.docx) and Excel (.xlsx) file, but get no results when I search for terms in them. However, if I save the same files as a previous Office version (.doc or .xls), then they show up in the search results. This happened in both a PDF portfolio and a regular PDF to which I attached the files.
I've searched online and through the forums, but no luck. I've also looked through and can't find any preference that would affect this part of search. Can anyone point me in the right direction for some help? I posted a similar question just about the portfolios last week and got no response, but decided to try again since it's also happening when searching the attachments.
Thank you!