I thought he had plenty to do back when he was doing his thing with Damian. And, as much as I don't like it, he's front and center in Legion. To the point where it almost feels like they're building him up to be an even more annoying Christ figure than Zack Snyder's Superman.
The only time I can think of where Jon's a central(ish) character but doesn't do anything is in Jurgens' Action run. Which makes sense. That series is about his Dad. Not him.
Sure I'd love to see him in more stuff. But aside from being a supporting character for Clark and having his own series (be it Super Sons or Legion) what more does he need to do? He's already been doing quite a bit.