The A320 family as I have stated before climb very slowly . When the rate falls to around approximately two hundred feet a minute they fly level. They accelerate a few knots past the target climb speed and then pitch up again and resume climbing. This is repeated until the aircraft reaches its cruise level.
The ground speed from FR seems very low for a climb in a heavy aircraft. If the aircraft speed falls to below green dot at high level it will neither climb or accelerate and a descent will be required to accelerate the aircraft and allow climb to be resumed.