What I mean is, can Construct only accept a certain number of buttons being pressed at once?
My platform game has an action that requires you to be holding Shift, Left Arrow, and Up arrow. If you do it in the air, and you're still holding the Space key from jumping, it won't work -- is that because you're holding too many buttons at once? Same thing happens if you're holding all three on the ground and try to jump then -- you simply don't jump.
Maybe it's a completely different problem, since the first move seems to work fine when holding Shift/Up and Right instead of Left, and you can jump while running to the left and holding all three buttons.
In other words, I have no idea what's going on.