Automation rules which are configured with the trigger "Issue updated" does not run when the parent Epic field is updated is next-gen projects.
From the issue history, we can confirm the change but the automation rule is not triggered.
1. Create an automation rule with the trigger "Issue Updated"
3. Create a next-gen project and create an issue of type Epic
2. Create a standard issue (Task, Story, etc) and update the Parent Epic.
As the Parent Epic was updated, automation rule with the trigger "Issue Updated" should execute.
Automation rule is not triggered
Current workaround is to create child tasks using "Add a child task" only which can then trigger "Issue Created".