Interesting report .
Let me speculate :
The pilots may have been trying to access the attitude and synthetic flight on the I pad foreflight or not .
both pilots distracted on I pads ? , nobody flying the aircraft .
Did not read any pilot take control after the auto pilot disconnected . Or any verbiage regarding the aircraft . You have control , I have control very important calls . More important than three green .

It is very important in a multi crew to know who or what is actually in control . When the auto pilot is on . It is flying . When I turn off the auto pilot I always say " I have control " annoys some folks who do not like non SOP language but I always do it . Good banter Squiiffy.

Needle Ball and Airspeed

The worst kind of attitude failure to have is where the attitude indicator appears normal ,but the actual aircraft attitude is not . Not fun a real mind melt as you are tormented as what to do .
The easy attitude failures are when the attitude indicator goes wild spinning like a washing machine . Distracting ,but after fighting the confusion you can fly partial panel easy enough if you cover the broken instrument .

Needle Ball And Airspeed .

The tough failures are the insidious quiet ones , sometimes just a flicker on the guage before it's happens , sometimes a big ball of flame shoots up past your arm and you know instinctively you are in a fight for your life.
​​​​​​One flag may not just be that one instrument , a whole system might be about to go , that Loose wire from that system might be about to give you a real challenge way worser than any training session.

Needle Ball and Airspeed .

I have had the pleasure of flying a 200 at night with an electrical fire , smoke filled , and the worst distraction was the FO crying and screaming about we are going to die . Flying the aircraft was the easy part , dealing with the emergency was easy , being next to a panicked human was the hard part .
I actually thought I might have to knock him out to survive .
Fortunately he calmed down when the smoke cleared.

Needle Ball and airspeed.

I will read it again .
You must learn from the mistakes of others as you will never live long enough to make them all yourself .

Needle Ball and Airspeed .

In you next moment of coitus , if your partner screams Needle Ball and Airspeed you will know they are proficient in partial panel flying :)

Aural Null - that's what's between the co-pilotis ears - or that is what that captain thought to his cost.

The difference between a professional pilot and an amateur. One uses SOP language so the other crew member knows what to expect. The other doesn’t..

Usually a flag on the pilot gyro is a dodgy inverter .
It may flag just before the inverter goes . Switching inverter on a 200 sometimes will drop the flag .
I have had a few failures over the years , not much fun in the Artic at night .

In case of distraction in this kind of situation I (and most of my colleagues in my bush pilot days) would carry the little rubber stick-on thingies that were used for partial panel training. Never had to use them in anger but they will simply life immensely!