When attempting to schedule new reports with an existing schedule in Advanced Scheduling, it allows you to go through the full process of creating the scheduled report (schedule, parameters, notifications, etc.) but is not actually saving that scheduled report.
Release : 16.0.3
a) Log into Clarity as Administrator
b) Home/Advance Reporting
c) Click on View/Schedules
d) Delete the existing schedule
e) Create a New Schedule Instance (You can then create Multiple Schedule Instance for the same report)