Can not pass _ga cookie to FB external _id parameter in Zaraz?

I tried adding the external_id field with the value from GA cookies in the Zaraz Facebook pixel. When I tried it several days ago, it was successfully passed, as I could see in the test event under the user data keys. However, today when I tried it again, it was empty. As a result, it is showing as an empty event parameter instead of user data keys.

Has anyone successfully passed a cookie value as a field value in Zaraz?

Thanks