The whole debacle is said to have upset Harry so much, Meghan had to tell her husband to "smile" as they entered.
This is the second shock video to come out from the reunion.
Footage from the family reunion, which appeared on social media, shows the Sussexes sitting in their seats in the second row, while Wills and Kate find their seats in the first row.
Earlier this week, The Duchess of Sussex, 38, surprised students at Robert Clack Upper School in Dagenham.
Meghan was there to help celebrate International Women's Day.
Addressing the male students, Meghan said: “Please continue to value and appreciate the women in your lives and also set the example for some men who are not seeing it that same way.”
“You have your mothers, sisters, girlfriends, friends in your life, protect them.”
“Make sure that they are feeling valued and safe and let’s all just rally together to make International Women’s Day something that is not just on Sunday, but frankly feels like every day of the year.”
Meghan and Harry bow out from official royal life on March 31.
Earlier in the week, Meghan wowed at the Mountbatten Festival of Music at the Royal Albert Hall.