Unable to return search results for .xlsx files

Issue Summary

Searching for text in .xlsx files is not returning the .xlsx file as a result.

Steps to Reproduce

1. Create an .xlsx document in Excel. Include unique text within the body. Attach to a page in Confluence.
2. Create a second Excel document, with another set of unique text. Save as .xls file instead. Attach this to a page in Confluence as well.
3. Ensure Confluence is reindexed.
4. Attempt to search for the 1st document with the unique text that was in the body. Searching for the 2nd document will return that document. Note that searching text in the title will still work. This issue is with text in the body.

Expected Results

Searching for text within an .xlsx file should return that attachment as a result, along with a preview of the text.

Actual Results

According to Search:

When you enter a search term, Confluence looks for content in all spaces (including personal spaces), pages, mail, personal profiles, and space descriptions. It also looks at the content of some attached file types (Word, Text, PowerPoint, Excel, PDF, and HTML).

However, searching for text in .xlsx files is not returning any results. When the document comes up in search results, it also does not preview any text from the document, only any comments in Confluence associated with the attachment.

When searching text in .xls file, it previews the first few lines of the spreadsheet.

 Confirmed that search of text in .doc, .docx, and .xls does return results.

Workaround

Save the spreadsheet as an .xls file.