Elon Musk loaned him money to buy his childhood home. Now, the billionaire is foreclosing.

In 2020, tech mogul Elon Musk agreed to sell one of his Los Angeles homes to filmmaker Jordan Walker-Pearlman and his wife, Elizabeth Hunter, for $7 million. Walker-Pearlman had grown up in the Bel-Air house—the longtime home of his uncle, the late “Willy Wonka & the Chocolate Factory” actor Gene Wilder—and Musk agreed to loan the couple most of the money they would need to buy it.

“He could have sold it for so much more,” Walker-Pearlman, a film director and writer, told The Wall Street Journal in 2022. “His sensitivity to me can’t be overstated.”

Four years later, an entity tied to Musk has filed a notice of default on the property, the first formal step in the foreclosure process, property records show.

Walker-Pearlman and Hunter have fallen behind on payments on the $6.7 million loan, according to the notice of default, issued in late July. The lender can force a sale of the property 90 days after the filing, the notice said.

Meanwhile, the couple has listed the house for $12.95 million with Drew Meyers of Westside Estate Agency.

Walker-Pearlman and Hunter are cooperating with Musk, Walker-Pearlman said. He is at peace with Musk’s move to foreclose, he said, adding that the billionaire isn’t being “adversarial or mean.”

“There’s no tragedy here,” he said. “Elon gave us a magical opportunity. I have no complaints.”

The filmmaker said the prolonged writers’ and actors’ strikes in Los Angeles last year played a role in the couple falling behind on the payments. The property is held in Hunter’s name, and she felt particularly uncomfortable missing payments, he said.

“She did not want to continue morally owing Elon anymore,” he said. “We already owe him such a spiritual debt.”

Walker-Pearlman said Musk’s representatives have made it clear that they have no intention of forcing a sale. Musk didn’t respond to a request for comment.

Located above the Bel-Air Country Club, the low-slung, white-shingled house has a kidney-shaped pool and guest cottage. Measuring about 2,800 square feet, it sits on a 0.78-acre lot. The exterior has a combination of traditional brickwork and wood detailing, while the interior features wood-beamed ceilings, fireplaces and an open layout.

Wilder, born Jerome Silberman, purchased the home for about $300,000 in 1976 following the success of his 1974 film “Young Frankenstein.” As a child, Walker-Pearlman split his time between Wilder’s house and his grandmother’s home in Harlem. His own parents, he told the Journal in 2022, were “a little crazy and not enthusiastic about the responsibilities of child rearing.”

While staying with Wilder, Walker-Pearlman said, he listened while his uncle read scripts and played the piano. He also recalled Sunday visits from the likes of Mel Brooks and Sidney Poitier. “That was my home schooling,” he said.

Wilder sold the property for $2.725 million in 2007, records show. He died in 2016.

In 2013, a trust linked to Musk, the CEO of Tesla and executive chairman of X, bought the property for $6.75 million, records show. It was located across the street from his main residence at the time.

In 2020, amid a mass selloff of his physical possessions, Musk put the house on the market, saying he wanted the buyer of the Wilder property to preserve it.

Walker-Pearlman and Hunter, a screenwriter, couldn’t afford the price Musk was asking — $9.5 million—but they came to a deal nonetheless, with Musk agreeing to loan the money to buy it.

Walker-Pearlman said he has fulfilled his own dream of restoring the house, and having his wife experience it.

“This is likely the closing of a very unicorn and beautiful chapter of our lives,” he said. “I’m not disgruntled at all.”

Write to Katherine Clarke at Katherine.Clarke@wsj.com