Millie's family moved back and forth between the US and the UK for years while trying to launch her career. At one point, they even needed to borrow money from Millie's manager. Millie told the Daily Mail that when they moved back to the UK for the last time, "I was devastated. I wasn't getting work. I thought I was done," and that she had met with a casting agent who had told her she was "too mature and grown up." But just after that, Millie landed her role on Stranger Things and her life changed.