As some of you know, your Advanced Movement is no longer working. This is because with the newest update the controls have changed. It is no longer bound to your spacebar it is bound to user action 1. This means you need to bind this to a User Action.
Step 1: Hit ESC
Step 2: Click Enhanced Movement on the bottom right.
Step 3: Set/Keep your Jump/Climb to user action 1 (or any action. You just need to remember it)
Step 4: Go to your Arma 3 Controls on the bottom Left. Go to the Custom Controls by selecting Show.
Step 5: Set your User Action 1 (or Other if you changed it in Step 3) with the key you want to use.
(Make it the space bar).
Step 6: DONE