As above, the wing ( including flaps) will produce lift all the time there is a (sub-stall) angle of attack and an airflow from ahead. In a still-air hover, there is no lift BUT there is resistance to the downward movement of entrained air over the airframe. This means that flaps will increase this resistance unless they are "down", thus reducing the plan area of the wing. This vertical "drag" will off-set some of the vertical thrust, thereby reducing the weight at which a hover can be established.
Aerodynamics get a bit complex in the hover!
Mog