GetInputKeyTimeDown not working on multiplayer?

I’m trying to capture how long the player has a key pressed down to determine whether to fire a charged attack or not. I read about the GetInputKeyTimeDown function which is available from the PlayerController. I’ve managed to make it work whilst playing as the server. But when I try to play multiplayer and run a dedicated server, the function always returns zero. I’m attaching the blueprint code. Anyone know if I’m doing anything wrong?