he used them in the last Outsiders story (Fear State) by Brandon Thomas, and he also used them in Robin King and Secret Files by Tony Patrick. he also used his powers pretty regularly in Hill's Outsiders, granted it was mainly his shadow powers and they did nothing every time he used them, but he used them. i guess it feels like we don't see them often because his primary ability is sensory based and he's a bat-character, so a lot of writers tend to write him in more of the hand to hand and gadget style of the other bats. however, I'd say the REAL reason is he just doesn't have enough material where he's given the room to show off his powers.
he uses his powers in almost all of the stories where he's the focus (except Future State admittedly) but Duke doesn't get a ton of material where he's being centered. the only time I can think of where Duke was a supporting character and his powers were showcased was in The Unexpected #4, most of his other supporting roles he's typically more of a cameo appearance with little room to do much of anything.
as for his powers in Signal & The Outsiders, I think we're gonna see BT do something similar to what he did know Fear State and have Duke's powers on display in the finale in the next issue. especially since it'll involve his mother and whoever kidnapped her (likely Gnomon but who knows we might get a curveball), so it likely means Duke being a metahuman is going to be at play in some significant fashion.