Ds already attends three enrichment classes for at least half a year now. He loves the classes- he's been pining for them to restart because they broke for the hols. He loves the class subject (robotics, math, science) and the teachers, and says the kids are fine but doesn't see them as friends. They're all noisy fun classes with loads of interaction opportunities with kids of mixed ages. It's just been an absolute no-go.
I'm starting to wonder if it's a peer thing. I never gave that much weight, thinking friendships should be based on common interest. That's still true, but possibly with an added dimension.