We had the same issue with the message ""Object reference not set to an instance of an object"" after creating a new schedule and restarting the App Server and associated services. One work around until BP comes up with a fix is to manually update the schedule and all tasks under the schedule again. This would make the schedules running again automatically. But we had an instance where only one of the tasks under the schedule where updated and the Bot picked up only that task while it skipped all the other tasks under the same schedule, and no errors were reported in this case.
William Lawrence
Sr. Automation Developer/Controller
Equitable Life of Canada
Waterloo, Ontario, Canada
+1 289 980 6526