The Pelicans announced Williamson had to attend to "an urgent family medical matter" and will rejoin the team at a later date:
Pelicans head coach Alvin Gentry later told reporters he does not know when Williamson will rejoin the team.
"We’re not concerned with the basketball side, we’re concerned with his family," he said.
Under the NBA's health and safety protocols established for the Orlando campus, players are permitted to leave because of an illness or family emergency without penalty if they receive preapproval from the NBA.
Per ESPN's Tim Bontemps, anyone who leaves the campus with approval from the NBA will quarantine for four days upon returning under either of the following conditions: They are gone fewer than seven days and test negative for COVID-19 each day they are gone, or they have an extended absence, undergo daily testing and test negative for at least the seven days before they return.
Pelicans executive vice president David Griffin didn't specify when Williamson would return to the team.
New Orleans (28-36) is 3.5 games behind the Memphis Grizzlies for the No. 8 seed in the Western Conference. The Pelicans' first game in the season restart will be July 30 at 6:30 p.m. ET against the Utah Jazz.