Keep momentum and same time ignore input while jumping?

I have this player character that has platform behaviour and I want it to jump and have no control of its movement in the air. I tried using this "ignore input"-action event while not in floor. This makes it so that when the player jumps it hits dead stop and doesn't move sideways any bit, only up and down. I want to keep the momentum the player had just before starting to jump. How do I do?

You could try this to go along with the ignore input...

"Simulate control

Simulate one of the movement controls being held down. Useful when setting Default controls to No..."

https://www.scirra.com/manual/86/behavior-reference

So if you are jumping left, ignore input but simulate platform pressing left.

I've never tried it so it may not work quite how I imagine, but it may be worth a shot.