This is not uncommon. What it means is that your ability to utilize fat for fuel is relatively low compared to your aerobic capacity. Note that your Fatmax is .5gm/hr. We see well trained endurance athletes able to use over 1gm/hr. Your 2.0 mM/L AeT is quite high relative to max HR. I do not think you hit your AnT or maximum steady state pace. See how the Pace vs HR graph is completely linear? When you hit your maximum steady state it will become non liner so that each faster increment in pace will give a smaller and smaller change in HR. We do not see any nonlinearity. This could be because the stages were too short and you never reached your maximum steady state.
To improve your ability to use fat you will need to train near the fatmax point. That will gradually approach that 2mMol point. To increase the aerobic capacity you will want to train at the 2mMol point. So, for a while these will be different types of training.