Hey chris, here's an example:
Basically I unchecked the "Default controls" option for the platformer object and simulate the controls of jumping and falling through, because I see in your example that this is the only controls you need.
Hope it helps :)
Holy crap that was easy, I feel a bit stupid. Thank you so much!
Also in the example you don't even need to mess with the x, simulate left and right still works. The fix was literally just a check box and a up key = jump event.