When MMTel AS sends CCR (Update Request) after called party answers, then MMTel AS doesn't wait for the CCA-U. MMTel AS forwards the received 200 OK (initial INVITE) immediately to the served user.
When MMTel AS sends CCR (Update Request) after called party answers and call diversion is detected, then MMTel AS waits for the CCA-U, otherwise MMTel AS forwards the received 200 OK (initial INVITE) immediately to the served user.