Hi @Anonymous,
Thanks for sharing that screenshot.
In the original article of Norm I see he was using the SiteName value and the Group column name of the SharePoint Demo list. In your screenshot it looks like it is missing the SiteName value, it only says ' Members'.
That is probably the reason why it returns empty. It cannot find a group called ' Members'.
Can you share a screenshot of the config of your whole flow and also that specific action? Did you use the same expression as Norm as well in the URI?
concat(variables('varSiteName'), ' ', triggerOutputs()?['body/Group/Value'])