I had the same issue as nd0 with the latest version of the workflow.
I debug it and found it's because there's a curly brace in my Notion cookie, but SimpleCookie stops parsing at the curly brace, which will lead to no notion_user_id in bakedCookie. Since your code only needs notion_user_id, I extract it with regex and it works for me now.
I can pr the code if that's helpful. Thanks for this amazing workflow!