Seems one of the castings was unnecessary, but that’s not it. Works fine on my computer with or without casting to BP_Grid_Manager. Not seeing anything obviously wrong with your verion either. Try relplicating what I’ve made and see if you can get it working (blueprintue link here). Remember to set auto recieve input to Player 0 so that input keys are registered, and again make sure Grid Manager Ref is set to BP_Grid_Manager as its default value in its variable properties.
