Prior to CB1610 A restart flag is set and the update is installed after the computer restarts.

Its crazy on CB 1710.. I suggest you to schedule O365 deployment in non business hour or use computer restart setting in client settings.

In Configuration Manager version 1706 and Above, I have note the following details:

The notification and countdown dialog could start while the user is not actively working on the device, for example when the device is locked overnight, so it’s possible Office apps running on the device could be forced to close to install the update. Before closing the app, Office saves app data to prevent data loss.

If the deadline is in the past or configured to start as soon as possible, running Office apps might be forced to close without notifications.
If the user installs an Office update before the deadline, Configuration Manager verifies that the update is installed when the deadline is reached. If the update is not detected on the device, the update is installed.

The in-app notification bar does not display on an Office app that is running before the update is downloaded. After the update is downloaded, the in-app notification displays only for newly opened apps.

For Office updates triggered by a service window or scheduled for non-business hours, it’s possible that running Office apps might be forced to close to install the update without notifications.

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