From the Final Report
At 2 h 10 min 05, the autopilot then the auto-thrust disconnected and the PF said
“I have the controls”. The aeroplane began to roll to the right and the PF made
a nose-up and left input. The stall warning triggered briefly twice in a row. The
recorded parameters showed a sharp fall from about 275 kt to 60 kt in the speed
displayed on the left primary flight display (PFD), then a few moments later in the
speed displayed on the integrated standby instrument system (ISIS). The flight
control law reconfigured from normal to alternate. The Flight Directors (FD) were
not disconnected by the crew, but the crossbars disappeared.
When the ASI came back, the bars reappeared and the AP would have been be available again.