Network,
I'd say one of two things is at play here, either your version of Project 2016 is not fully updated or you have some file corruption.
The latest version of Project 2016 is Winproj.exe 16.0.4705.1000. If that is not your version, run Windows Update. Note, if you are using a subscription form of Project, it is automatically updated.
If your version is fully updated, then you might have some file corruption. Try saving the file as XML. Then re-open the XML file in Project. Note, you will lose any custom formatting with this process.
Hope this helps.
John