I’m glad you solved it. I haven’t had to resort to using the Creator field yet. The Creator field is automatically filled when the db record is created, while a User field would have to be intentionally filled in an earlier workflow. Another common issue devs face is if their privacy rules prevent the viewing of some or all fields. Maybe you set a privacy rule on the User field but not the Creator field. Another possibility is you could have set the User field incorrectly (for example, setting it to This User instead of Current User)–although, depending on your use case, they could be the same thing.
Devs disagree with one another about whether it’s best practice to use the Creator field or add a User field and use that instead.