I think that what is the case is that something else consumes the input before your pawn or controller receives it. Check out this page for the order in which objects are given the chance to use input: Input | Unreal Engine Documentation
You want your playercontroller to capture it right? Or the pawn? The page also mentions you can make any actor highest priority by re-enabling accepts input. Not sure what the bp node for that is but maybe you can find it. Hope this helps!