Ruling on the imam not acting on the congregation’s notification of his forgetfulness

Question:
The first message in this episode is from one of our brother listeners. He says: Muhammad Naji Mayyub from Makkah al-Mukarramah. Our brother has a number of issues, among which is one in which he says: We prayed Maghrib behind an imam, and in the second rak'ah he prostrated, forgetting one prostration, and then stood up for the third rak'ah. So we said to him, “Subhan Allah,” but he did not respond to us. We continued the prayer with him until he said the closing salam. Then we told him what had happened, and he stood up and performed a rak'ah, and prostrated for forgetfulness before the salam. Is what we did correct?

Answer:
In the name of Allah, the Most Gracious, the Most Merciful. Praise be to Allah, and may Allah send prayers and blessings upon the Messenger of Allah, and upon his family and his Companions, and upon those who follow his guidance. As for what follows:
What the imam did is without blame, and there is nothing wrong with it; because the rak'ah in which he left the prostration was invalid, and he performed a rak'ah in its place, and praise be to Allah, there is no blame in that. And when you notified him, perhaps he was not convinced by your notification, and he did not pay attention to what you intended, so for this reason he did not do anything. Yes.

The presenter : May Allah reward you with good, and may He do you good.