What is needed is a sum-up of the previously covered aspects.
I aggree.
One thing (I think this is correct): More Airspeed, more Drag. So the lack of "positive thrust" could be explained by the higher drag (or higher airspeed) around time tag 30.
I ask anyone (maybe you know) what is the correlation between N1 and thrust in KN (is it specific to the engine - an IAE V2527-A ?).