We are using Office 2010 and SharePoint 2013. The issue happens for XLSX (Excel files) and but NOT for XLS (Excel) and Word (DOCX and DOC) and PowerPoint files.
I found related posts that try to address these such as: https://social.technet.microsoft.com/Forums/office/en-US/d724a882-66cf-4515-a088-afd7d088b103/email-link-to-share-documents?forum=sharepointgeneralhttps://social.technet.microsoft.com/Forums/office/en-US/d724a882-66cf-4515-a088-afd7d088b103/email-link-to-share-documents?forum=sharepointgeneral
Solutions have been proposed as well as workarounds such as removing the ?web=1 in the URL or saving the XLSX file as XLS. I find these not user-friendly especially if someone is trying to use the Share button. I wonder if Microsoft has a KB fix and why this is happening only for XLSX files.
