you should be getting an error code back on the reject, see this similar thread they had "IND-996 - The Dependent/Qualifying Person Identity Protection Personal Identification Number (IP PIN) provided on the return is not valid" and had to create/add pin for dependent to complete the filling.
https://ttlc.intuit.com/community/taxes/discussion/ip-pin-is-correct-still-rejected/00/3653854
