The last update we pushed out was 16.18.0 so not sure if this was implemented in 16.19.0 but running the 16.20.0 update packages listed here: https://docs.microsoft.com/en-us/officeupdates/release-notes-office-for-mac#december-2018-release causes the respective office products to force close without prompt the user to save the unsaved documents.
In the previous updates packages, you could run the update while the office products were open and when the user quit and re-open the office product, it would run as the updated version.
Is this what everyone is experiencing or did I get a faulty update packages?