A family of Microsoft word processing software products for creating web, email, and print documents.
I had this issue persistently last year but it seems fixed now with latest releases all round. I suggest running Microsoft Autoupdate, and doing manually every few days too. Also join the optional Office Insider program to get latest fixes.
My system:
Word for Mac 15.32 (170201)
MacBoook Pro (2016), 10.12.3