Am creating a simple flow to populate an excel file with the details of people that have access to a PowerApp. I want their email address, their roleName and the createdOn date.

Above image shows the flow structure and it works fine for Email and roleName and the excel file is updated correctly, so the Compose and Compose 2 steps work okay.
However, because createdOn doesn't appear as an option in the Get App Role Assignments list, I tried using a dynamic expression for Compose 3:
items('Apply_to_each')?['properties/createdOn']
But saving throws this error:
Flow save failed with code 'InvalidTemplate' and message 'The template validation failed: 'The repetition action(s) 'Apply_to_each' referenced by 'inputs' in action 'Compose_3' are not defined in the template.'.'.
This is a copy of the first record of the JSON for the array so you can see the items:

So createdOn is there within the properties part, but for some reason I can't access it like I can others. I can even get the scope and the notifyShareTargetOption, but not the createdOn or createdBy.
Am I missing something here? Anyone explain how I can extract the createdOn date ?
Thanks