Ashley St. Clair, the mother of one of Elon Musk’s 14 publicly known children, claimed Tuesday that she turned down $40 million offered by the Tesla CEO to sign a non-disclosure agreement about their relationship. Musk denied the claim Wednesday, but his willingness to engage with the publicity surrounding the new movie that St. Clair was promoting seems likely to help it succeed at the box office when it’s released in late October. The documentary, simply titled Musk, premiered at the Venice Film Festival in Italy on Tuesday, where St. Clair and the film’s director Alex Gibney held a press...