Deployed Software Updates in Patch Management Solution 8.0; configured the Default software Update Plug-in Policy > Restart tab as follows:

Client runs the Software Update Cycle on schedule and reboots at the end per settings. When the deferral popup for Restart to finalize important updates is presented; selected Postpone option and allowed deferral for maximum time (1 hour by settings displayed above).

Found that following the maximum time, the Restart to finalize important updates popup was presented again without the Postpone option, and the popup remains without being closable and is able to be minimized as follows:

Expected behavior: the Client should force reboot following this popup after the maximum deferral to restart has been reached.

The setting Allow user to defer the restart is not intended for immediate restart when configured by itself, for it needs to be accompanied with the setting Restart automatically after for that will reboot the Client following the Software Update Cycle.

See the Blue 'i' information details on each setting as follows for each of these settings as follows for affirmation:

This is working as designed.

To force reboot following the max deferral time conclusion; configure the Restart automatically after for the desired time of allowance past the deferral period. 

Note: The nag configuration setting was added per INFO4517 in Patch Management Solution 8.0 HF7+

As in the example configuration above; user is to receive the '1 hour' deferral notice, and the administrator would like to force the restart just after that time, so the Restart automatically after could be configured to a consecutive time past the deferral time, for that is when the deferral period is complete and the popup notification will then show without 'Postpone' and a forced timer countdown reflecting the set time in the Restart automatically after configuration.

The user will then have the only option to wait out that set time or select Restart Now as follows: