“Kate Plus 8” fans are questioning the absence of Collin Gosselin (left), who is pictured with his sextuplet siblings, from the family’s photos. TLC

Kate Gosselin hasn’t made her struggles with her son Collin Gosselin a secret, but that doesn’t mean she’s ready to share details about his issues with the world.

On Tuesday evening, the “Kate Plus 8” star posted a photo of five of her children to Instagram. The shot showed her 13-year-old sextuplets Hannah, Leah, Alexis, Aaden and Joel smiling in their Halloween costumes. “I had a trick-or-treating date with a couple of cute pink dinosaurs and a few adorable astronauts,” the mother of eight captioned the picture.

While the shot was clearly meant to be a positive update for viewers of their TLC series, not every fan of the family was taking it in stride. Many commenters have posed questions to Kate on the post about the whereabouts of her and ex-husband Jon Gosselin’s 13-year-old son Collin Gosselin.

“Still no Collin?” asked one fan, a similar statement repeated on the post.

“No Collin? This is sad. It’s like he’s not even a part of your family anymore…Imagine how Collin feels,” reads another comment. “Collin should be home. This is terrible,” wrote one viewer.

“So sad there are hardly pics of Collin in these memories,” another fan posted.

Some commenters even suggested the family, which also includes 17-year-old twins Mady and Cara, disappear from the limelight for their own well-being. In recent years, the family has being struggling not only with Collin, but also with custody issues.

“This show is just depressing and unsettling now,” reads one comment. “The ugly divorce and all the accusations, the behavior of the older girls on national television, the disappearance of Collin, Kate’s erratic behavior...it’s time to pull the plug on this show. There is nothing ‘cute’ about it anymore.”

Others have simply expressed their well-wishes for Collin and the rest of the Gosselin family. “I hope Collin is doing well” reads one statement.

“I’m sure Kate is trying to do her best for all her kids and when she’s ready to update viewers/fans she will. I hope everyone wishes her and her children well,” posted another fan.

Kate received similar questions about Collin’s whereabouts over the summer when she posted a photo from the sextuplets’ 13th birthday. “Where is Collin is the million dollar question that everyone is asking,” reads one of the current top comments on the post.

“This year [was] much like last year. Obviously the difference is that Collin wasn’t there,” Kate said during a “Kate Plus 8” episode that showed the birthday celebration. “I am comforted with the fact that my kids, all of them, each unique child, is receiving exactly what they need and that hasn’t changed. I’ve said that before, I’ll say it again. It’s a bittersweet moment. We’ve had many of them.”

Kate revealed Collin was living away from the family’s Pennsylvania home in August 2016, telling People Magazine that her son has “special needs.” Jon followed up on Kate’s comments by saying he was told that Collin was attending a school for children with behavior problems.