Have you tried repairing the Office installation (via Windows Control Panel > Programs > Programs & Features > Microsoft Office (version) > Change > Repair)?

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Cheers,
Paul Edstein
[Fmr MS MVP - Word]

I thought about several options:
1. Completely uninstall office 2016, then reinstall it.
2. If fails to fix, roll back Windows to before the CU.
3. If fails to fix still, uninstall 2016, and put 2013 back on.

But first try will be the "repair".
(It IS up to date btw- found how to check)

Thanks