We're trying to set up better document management … including consistent use of metadata

• a .doc file (Microsoft Word 97 - 2003, according to the Windows 7 file explorer) has information entered in the Keywords field of the Summary properties; this information is displayed as "Tags" if I open the File tab for the document and select Info, and under "Tags" in the file explorer
• a .docx file (Microsoft Word Document, according to the Windows 7 file explorer) has information entered in the Keywords field of the Summary properties; this information is displayed as "Tags" if I open the File tab for the document and select Info, but not under "Tags" (the Office attribute "Keywords" is not available)in the file explorer

question: what's to do to make the Keywords (aka Tags) metadata from a .docx visible in the file explorer?