Thanks for the feedbacks The Rock and Chris.
So, I realized that I need to use the add-data-center-object REST API call in my python script to import the useg epg ACI object into checkpoint. The thing is, the IP associated with the useg epg isn't shown up on the CP's imported object.
I compared the good imported useg epg (that has the IP shown up. Sometime back, not sure how it was done) to the useg epg I just imported into CP, the DynamicProperties and Ipaddr fields are set to the useg epg's IP. Why are they blank now?
I used the following API commands:
url = f"{url}/add-data-center-object"
body = {"data-center-uid": data_center_uid, "uid-in-data-center": object_uid, "details-level": "full"}
session.post(url, json=body)