Hi @chevychaser, we are working on a solution now and expect to release that next month. It will include the notification not disappearing unless the device user closes the notification or the device reboots after the 15 minute notification window. The notification will state what time that device will reboot which will be based off the 15 min window so if it appears at 10:07am, the device will say it will reboot at 10:22am. This notification will also have a Reboot now button should the user be ready for a reboot before the stated time. The notification will be on if a policy has Automatic Reboots turned on. If the auto reboot setting in a policy is off, the notification will not appear.
We are concurrently working towards a deeper solution to include deferrals, configurable reboot times, messaging etc. We do not have a timeline for that feature release yet.