Laravel object values don't exist, but then do if json_encoded

There's something weird going on in my Laravel query.

So I'm getting a collection of Users - if I run it through json_encode, all its keys/values are there. If I don't, some of them are null. E.g:

        Log::info(json_encode($user)); // 'tasks_from_columns' exists
        Log::info($user->tasks_from_columns); // null
        Log::info($user->email); // exists?
        Log::info(get_object_vars($user)); // 'incrementing', 'exists', 'wasRecentlyCreated', 'timestamps'

There's a relation on the User called tasks_from_columns. It's there if I json_encode it, but null if I try to access it directly. Most other keys are accessible though, like email, id etc.

If I run it through get_object_vars, none of them are shown. Just some other ones shown above.

Anyone know what the deal is?

The query itself is

        $teamWithTasks = Team::where('id',$team->id)->with(['users' => function($query) use($team){
            $query->with(['tasksFromColumns' => function($secondQuery) use($team){
                $secondQuery->where('created_at','>',Carbon::now()->subDays(365))->with('project')->whereHas('project', function($thirdQuery) use ($team){
                    $thirdQuery->where('account_id', $team->account_id);
                });
            }]);
        }])->first();

via Chebli Mohamed