Looking at the last screen shot you posted…Your still flying way to fast to maneuver the A320. Your flying at 350 knts, it doesnt matter what your throttle is set for, if you flying at 350 knts the autopilot will not let you do things like ascend or descend. Before you try to climb or descend, lower your airspeed to 280 knts, then try again, it should then work, once you have reached your desired altitude and are flying straight and level you can return you speed to the 350 knts again. Until you need to maneuver again, then you’ll have to slow down to repeat…