I am trying to build an automation that adds watchers to a ticket based on being added to a custom people field.
Custom Field is Support Players and I set if the field changes on create or edit.

Which should trigger an action to Add Watchers (screenshot below is me trying to use what I think is the custom field ID but it didnt work)

I have tried many variations of referencing the Support Players field but nothing works. I keep getting an error that looks like this:

Does anyone know how to use a People field and have those people become watchers to the tickets? Any help is greatly appreciated!