A few users have reported intermittent problems with chimes not always chiming after upgrading to iOS 9. Once the circumstances that trigger this issue are identified and the problem is fixed, an update will be posted. Additionally, a slight delay when striking the hours has been introduced with the upgrade that will also be corrected soon.
A change in iOS 8 makes it necessary to enable notifications in order for the chimes to sound when Grand Clock is not running.
Go to the Settings app and select Notifications. Scroll to find Grand Clock, select it, and enable notifications.