How can I get a GUI button to Invoke Unity Events from my player action map?

I had an on-screen button that rotated my game board 180° (and buttons to rotate incrementally as well) using the new input system but I lost all my code.

After recreating the rest of what I had of my game I cannot figure out how I bound my GUI buttons to my player's key presses.

I've added an "On-Screen Button" and linked it to the "E" key, which is mapped to an action called FlipBoard in my Action Map. When I use the keyboard by pressing "E" it works fine, but clicking on on-screen button with the mouse doesn't work, even though the colors change properly when pressed.

Is there another way to link a GUI button to a key press or a Unity Event defined in the Player script (shown below)?

 public void OnFlipBoard(InputAction.CallbackContext _0)
 {
     FlipBoard();
 }

Thanks in advance.