I don't feel its that contradictory that Adrien was both on fencing teams and basketball teams, and completely isolated as a child with only Chloe and Felix as his friends.
Adrien at times, though it could be due to the show being from Marinette's pov, can come off as aloof. Even with Nino, who is his best friend, he keeps a distance (which makes sense considering he is Chat Noir). Adrien's character has been stripped a lot since seasons 1-4, but even back then he was much more expressive as Chat Noir than as Adrien.
Kids want to hang out outside of activities. Adrien wasn't allowed to. Kids want to connect on a deeper level, but Adrien as we see him is so attached to the Prim and Proper conditioning his parents forced on him that he comes off as a doll (though Ephemeral does imply this is due to Mari missing his more Chat Noir personality traits when hanging out with him). We even see it with his participation in Kitty Section. He's not close to any of the members, barely interacting with them with the exception of *maybe* Luka, and that's mostly because of Marinette (the episode at the ice rink with Luka and Kagami).
Adrien's participation in team sports could explain how he knows that taking personality traits from anime will go over well as Chat Noir, but it doesn't mean he wasn't isolated. He could be goofy and learn some social cues (such as that people respond well to anime references to tie this back to his chat persona) whilst still missing out on major social developmental milestones due to his home schooling. I've done team sports (volleyball) as well as pottery classes, art classes, etc. I left those classes without a single friend, and I barely talked to 90% of my volleyball team. That's without the awkwardness many home schooled people report (though my autism probably brings me to a similar level as those who were home schooled, or at least close enough to feel comfortable comparing my experiences to his).
Obviously the Adrien we know probably tried to reach out, but I don't think its a stretch that Gabriel and Emilie ruined any potential relationships he could have formed, or that Adrien simply came off as Too Much. If he leaned more chat noir, then we know some people find him obnoxious. If he leaned more Adrien the Brand, then we know many people find him cut off and lacking inner depth - they see him as "nice" and nothing more (compare how seasons 1-3 Nino treats Adrien to the rest of the class - Nino seems like the only one who actually knows him. This is even in ephemeral where Nino isn't phased by his puns and silliness the way Mari is, or in Lies where Kagami shoots down his silly poses while drawing.)
As for why he doesn't have model friends... I'll just say it. Adrien, as he is depicted, is a total nepo baby in the modeling industry. We only ever see him do shoots for his father's company. Closed shoots at that, where he is the only model. If the show let him be an actual super model, like we are told he is, he absolutely would know other teen models (though the above would explain why he's not friends with them, with the added pressure of technically being competitors). Adrien's modeling career, as we're shown it, wouldn't open him up to meeting too many other models. If he were treated like an actual model in the show, then there's more wiggle room to question shit, but as it is the only people I think he should have a relationship with would be the other ladybug movie voice actors. Those being professional relationships, they would only know him as his Adrien the Brand persona.
Yes this is me doing the work of the writers for them, trying to make sense of how he was simultaneously isolated and involved in group activities. I just find this to be less of a contradiction than other writing issues with the show due to my own experiences. Adrien's character has many inconsistencies, especially in later seasons, but strangely enough I don't think this is one of them.
