I do a lot of FRAs on various buildings but never a block of flats and if it were the cause I would seriously question whether I would have noted the external cladding, I will now.
Having seen the pictures, there's no doubt that the cladding is flammable. I'm sure someone will end up inside for this.
1 architect got the spec wrong
2 company supplied wrong material.
3 manufacturer cutting corners
4 fire testing lab got it wrong.
Or
5 Unqualified installers cutting corners and/or using cheap fixings.
One of them will end up inside.