Likewise, I've seen it react pretty lazily to small (1000-2000ft) altitude changes in OP CLB/DES mode.
It's smart aircraft. It does lot of things for you. FCOMDSC-22_30-70-30 P 3/4
Note: If the change is less than 1 200 ft in OPEN CLB mode, the aircraft responds with a rate of climb of 1 000 ft/min.