That is a very high Aet, as measured by lactate levels. Although your fat crossover is well below this, could it be that your crossover hr is not too low in terms of %age of max hr? (eg 20 bpm below 171 bpm, is not a low hr for training).
What is your AeT and crossover in %ge of max hr?
I suspect the advice from here, will be to do most of your aerobic runs at intensities up to the crossover hr?