For me enable the Preview in the Explorer solved the problem.
That solved it for me.
Well, really, it was NOT using details pane. So either using Preview Pane (which turns of the details pane in favor of the preview pane) or no right-side pane at all fixed it for me. After searching for 4 hours.
For me File Explorer Hung forcing me to click X then close application.
Other file extensions worked perfectly: .wmv, .jpg, .txt, .rtf, .pdf, even .doc, .xls, .ppt.
Only ones that caused explorer to hang were: .docx, .xlsx, .pptx.
Clicking on them, right clicking on them, or double clicking (to open) them.
And only with Windows 10 File Explorer details pane turned on.
Windows version 1909 with current updates as of 12/13/2020.
Office 365 subscription with Office 2019 updated as of 12/13/2020.
Also discussed here:
https://www.tenforums.com/general-support/148355-file-explorer-preview-pane-crashing.html
and here:
https://techcommunity.microsoft.com...ile-hangs-explorer/m-p/213167/highlight/false
these folks suggest repair install of MS Office:
https://answers.microsoft.com/en-us...y-office/ba9a41c0-ac31-4cd2-993e-8642038f3c71
Repair install also suggested here:
https://www.dell.com/community/XPS/X...s/td-p/6054441