Hello, I figured it out:
I had to modify the rule from Walking to InAir. Now it checks if the player is Falling and is NOT IsAiming.
Also, I had to remove the Exit Aiming function when the player switches MovementMode from Walking to Falling.
Now the player can keep aiming when falling
Edit:
I am now trying to get the player to be able to aim any time while they are in the air but I need some help. So far, when the player is in the air and I aim, the crosshair dissapears but the animation to aim down the sights never starts. Any ideas? Thank you.