I am trying to restrict wrong assignment of tickets to users by creating an automation that resets the field of assignee if anyone outside of my group of users tries to change the value. I have achieved this by using this to set user upon the automation trigger:
{{fieldChange.fromString}}
I have attached a screenshot of the error I am getting when trying to do this. It just says Inactive user even though this is an active user of my project and space. Can someone help me with what i need to do differently to avoid this from happening? 