If Checklist formatter is created and added on any form other than task:
1. There are 3 Checklist titles on the form, and selecting 'Create New' shows a loading icon that animates indefinitely but never completes the loading process:
2. On console client side error is thrown 'Uncaught Error: [$controller:ctrlreg] http://errors.angularjs.org/1.5.11/$controller/ctrlreg?p0=InlineChecklistCtrl':
The reason for the issue is because 'Angular Module' field for checklist Formatter is empty for the formatter you created, for example:
1. Fill "inlineChecklist" as angular module for checklist Formatter. Open formatter table and look for your Checklist formatter
Add 'Angular Module' field on your list and add 'inlineChecklist' on the table you are showing Checklist on.
2. Flush the cache after making changes.
Note: Make sure the Checklist formatter you have created is in Global Scope
If this doesn't resolve your issue, here is another cause of the same issue