Office 365 SharePoint site does not allow "Edit in Word Online"? Possible reasons?

I recently uploaded a Word document to an Office 365 SharePoint site.  I am able to "Edit in Word" from the site.  However, the "Edit in Word Online" is not available (greyed out).  I assume it is because of some content in the Word document.  Others are working correctly.
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ticgumsConnect With a Mentor Author Commented:
I found the problem... It was saved incorrectly as a template (dotx).  I correctly saved as a document (docx) and it now works as expected.  SharePoint generally hides the extension.
Vasil Michev (MVP)Commented:
If it only happens for one document, it's probably the document itself indeed. Can you open it OK in Word Online (i.e. make sure that the uploaded version is not corrupted)? Check also if it has been checked out, test with different browser, private session, etc.
Vasil Michev (MVP)Commented:
Good to know and thanks for sharing the answer :)
ticgumsAuthor Commented:
Problem was my error.  My Answer contains the full explanation.
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