Adobe Standard DC unable to combine .docx files

When I try to combine .docx files using "Combine Files" in Adobe Standard DC, I receive an error message that says: "Additional files will need to be installed to create PDF from this file. Do you want to run the Adobe Acrobat DC Installer in repair mode?" I have run the installer in repair mode, but nothing happens. I have also tried totally uninstalling and reinstalling Adobe, as well as repairing/uninstalling and reinstalling Microsoft Office (it's Office 2016). I am able to combine .doc files with no problem and I can print .docx files to PDF/use the plug-in in Word without any issues.

Any thoughts on next steps?

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