I have an automation setup to create a ticket in project 2 based upon a ticket going through a certain transition in project 1, I edit the newly created ticket and copy a number of fields, which all work as I expect.
The issue I have is I seem unable to set the assignee of the newly created ticket correctly, I've attempted using edit to copy the assignee field from the triggering issue and I've also attempted the using the assign issue automation, I'm getting an error in the automation which makes no sense to me:

The automation is advising there's no parent issue to copy the assignee from, but as you can see on the left I'm asking it to copy from the trigger issue (not a parent).
When I used the edit automation to copy the assignee field, it seems to incorrectly copy the reporter field.
Is this a bug or am I missing something?
EDIT: for clarity, Project 1 is a Jira Service Desk Project and Project 2 is a classic org administer Jira Software project.