Markle Sr. had left his home in Rosarito, Mexico on Tuesday night, the eve of his birthday, and drove the six hours in heavy traffic to check into a $130-a-night motel in Los Angeles.
Just a day after the interview was aired, Samantha Markle, Meghan's half-sister, started a string of tirade via social media.
A source told The Sun newspaper: "He's shocked about these claims".
"The whole story about Meghan's father undergoing heart surgery was made up", the source said.
Marie Claire reported that during Thomas's appearance on Good Morning Britain, he claimed he checked into the Sharp Chula Vista Medical Center.
However, the Daily Mail says it contacted the hospital for comment on his stay on May 16 but were told "no such name" had been admitted for a stay.
This is, of course, a far cry from the way that Meghan dressed herself when she was an actress, and before she got engaged to Prince Harry. Her father missed her wedding. "If anything, feel sorry for Meghan".
'Glad you have so much time to gallivant around paying tribute to others while ignoring your own father!' she wrote.
Meanwhile, Prince Harry, who chose a grey suit jacket and tan pants for the event, remained firmly by her side as they arrived at the Southbank Centre together, before they shared constant loving glances with each other inside. "Harry? I guess I was right" added Samantha, also bashing the handsome Prince, 33, after shaming her famous sister. "I don't like the one I'm seeing now", he said during the interview. This is a pained smile'.
While no one knows what is really going on behind closed doors at Buckingham Palace, one thing is for certain: the Markles aren't going anywhere, anytime soon.
"I think she finds it a little frustrating at times, but this is her new life, and she has to deal with it", the insider continued.