Arc Fault, GFI and Combo Breakers in a panel not tripping

[scottam99]

One of our customers called a home inspector who tried to test all of the GFI's Arc Fault and Combo breakers. A;; of them just Hum.
I'm thinking a neutral is to blame. Anyone have this happen to them? I can't believe it's faulty breakers as they are different.
Square D QO Type breakers

 

[retirede]

How were they tested? The only correct way is to use the ‘Test’ button on the device itself.

 

[tom baker]

AFCIs not tripping? That’s a first.