The Kardashian/Jenner family happily posed for a group shot, that included Caitlyn Jenner, Scott Disick, Corey Gamble and Tyga – but Rob was nowhere to be seen.
However his mother Kris, 60, has explained that Rob, 28, was present for the celebrations, but snuck off to visit friends before the picture was taken.
Speaking on US radio, the momager said: “He lives with Khloe, so he was around and then went over to a buddy’s house.”
Rob’s issues with depression and social anxiety have been well documented, and Kris continued: “He’s doing alright, he’s doing his best.
“He’s not as into being on camera as much as the rest of us, but he’s working on himself. He’s gonna be OK.”
Kris also addressed youngest daughter Kylie’s latest photo shoot – which saw her bare her bum and pose in a wheelchair.
She said: “The shoot is insane. This is so Kylie, by the way. Steven Klein shot this, and he’s so iconic and amazing. I love that my girls get to work with the most fantastic photographers in thew world, it’s such a great experience and it’s truly remarkable.”