When designing a Single Arc between 2 Strings, levels are usually correctly calculated inbetween. Sometimes they are not. How come?

When designing an offramp according to NL design standards, 145 options are used to widen the lane and make a fluent transition between the ongoing lanes and the exit lane: 

design,edit gapingen
145,b8a2,b8c0,mp30,4= 1800.000,5= 1.000,7= 1800.000,10= 1800.000 (line)
145,a8a2,a8c0,mp31,4= 1796.750,5= 1.000,7= 1796.750,10= 1796.750 (carriageway)
145,s8a2,s8c0,mp32,4= 1796.700,5= 1.000,7= 1796.700,10= 1796.700 (pavement layers)
145,z8a2,z8c0,mp33,4= 1796.600,5= 1.000,7= 1796.600,10= 1796.600 (pavement layers)
145,k8a2,k8c0,mp34,4= 1792.850,5= 1.000,7= 1792.850,10= 1792.850 (shoulder)

100,mp30, ,b8a2,4= 0.000,7= 0.000
100,mp31, ,a8a2,4= 0.000,7= 0.000
100,mp32, ,s8a2,4= 0.000,7= 0.000
100,mp33, ,z8a2,4= 0.000,7= 0.000
100,mp34, ,k8a2,4= 0.000,7= 0.000

100,mp30, ,b8c0,4= 0.000,7= 0.000
100,mp31, ,a8c0,4= 0.000,7= 0.000
100,mp32, ,s8c0,4= 0.000,7= 0.000
100,mp33, ,z8c0,4= 0.000,7= 0.000
100,mp34, ,k8c0,4= 0.000,7= 0.000
999

Usually, 145's provide fluent levels between both strings, but in this sequence the mp30 and mp31 create a bump in the design. I will use other design options to smoothen this out, but I'd like to understand the way 145 options assign levels inbetween. Kindest regards, Robin Bongers

Report mp30: 

Level            Level difference

-2.903 0.007
-2.896 0.012
-2.884 0.011
-2.873 0.011
-2.862 0.011
-2.851 0.009
-2.842 0.009
-2.833 0.008
-2.825 0.008
-2.817 0.007
-2.81 0.007
-2.803 0.006
-2.797 0.005
-2.792 0.005
-2.787 0.004
-2.783 0.004
-2.779 0.003
-2.776 0.003
-2.773 0.002
-2.771 0.002
-2.769 0.001
-2.768 0.001
-2.767 0
-2.767 0
-2.767 -0.001
-2.768 -0.001
-2.769 -0.001
-2.77 -0.002
-2.772 -0.002
-2.774 -0.002
-2.776 -0.003
-2.779 -0.003
-2.782 -0.003
-2.785 -0.004
-2.789 -0.004
-2.793 -0.004
-2.797 -0.005
-2.802 -0.005
-2.807 -0.005
-2.812 -0.005
-2.817 -0.006
-2.823 -0.006
-2.829 -0.006
-2.835 -0.006
-2.841 -0.006
-2.847 -0.006
-2.853 -0.007
-2.86 -0.007
-2.867 -0.007
-2.874 -0.007
-2.881 -0.007
-2.888 -0.007
-2.895 -0.007
-2.902 -0.008
-2.91 -0.007
-2.917 -0.008
-2.925 -0.007
-2.932 -0.007
-2.939 -0.008
-2.947 -0.007
-2.954 -0.008
-2.962 -0.007
-2.969 -0.008
-2.977 -0.007
-2.984 -0.007
-2.991 -0.007
-2.998 -0.007
-3.005 -0.007
-3.012 -0.007
-3.019 -0.007
-3.026 -0.006
-3.032 -0.007
-3.039 -0.006
-3.045 -0.006
-3.051 -0.006
-3.057 -0.006
-3.063 -0.001
-3.064