I like the Jira automation rule in the Template library called "Sum up story points when the field value changes," which updates the Parent's story points when a child issue changes or updates its story point value. I have it running Globally, and it works great, at least for the issues that changed AFTER the rule was turned on. There are thousands of Epics with no story points, even though the child issues have a story point value.
To clean up the existing Epics that need their child issue story points summed up and stored in its story point field. I thought it would be a simple variation of the running rule instead of triggering the automation of an issue story field value changing and summing it up to the parent Epic. It has turned out to be more challenging than I expected, so I thought I would check with the Community to see if anyone has already solved this rule construction.
The rule should be manually triggered; run a JQL query that finds all the Epics without story points. Then, sum the child issue story points and replace the Epic's story points with the new sum. So it will work from the Epic down when the Template rule works from the child issue up.
Many thanks, as always. Happy Thanksgiving, everyone! Whoever solves this gets an extra helping of turkey and dressing tomorrow. 