I have one server out of several dozen that I've scheduled patches on this cycle that won't kick off the actual patching that it shows as being scheduled. I've tried several times to reschedule, and it's been rebooted several times as well.
We would need to look at logs from the target machine. The logs can be found in C:\Windows\ProPatch\Logs and C:\Windows\ProPatch\Scheduler. (*.log). I could take a look at them if you zip and attach them to a response or you could open a web case.