Why is this problem occurring
This is currently a known Bug where if you have a Client(s) added via the Contacts Application and have Timers running.
The workaround for this is to do the following:
- Launch System Preferences > select Security & Privacy > select Privacy.
- Select Contacts from the list > uncheck Billings Pro.app in the list.
If the issue persists after following the steps above, please initiate a support ticket here for our Technical Support Team to investigate further.