speculation is...
For some reason , it looks like the ground shift relay was in
airborne mode during the take off roll. This would inhibit the take off
warning , which among other things , gives you a warning if taking
off in the wrong configuration.
If the flaps - for same reason - were not in the correct postion ,
there would be no warning in this case!!
Considering the TOW with 178 pax onboard and if they rotated at the
correct take off speed , but with wrong configuration , they were
some 15 kts below stall speed......