Understanding of Issue Property and "Checklists" custom field synchronization
Add-on uses "Issue Property" as first priority storage and then syncs it with the "Checklists" custom field.
It means that If you just create an issue and push values to the "Checklists" field - it will be loaded by the add-on. But if you then try to edit the "Checklists" field - the add-on will take the latest values from the Issue property and overwrite the custom field's values. We have plans on providing more control to administrators over that synchronization mechanism and which storage to use as the 1st priority storage.