Hi Henry
It looks like the variable MS_LEVEL_EDIT_ATTRIBUTE_LIST isn't set to allow you to edit the ByLevel colour
I have this set at the SITE level. But it depends on your requirements as to how many variations you have set. Some clients don't want the ByLevelColor set
MS_LEVEL_EDIT_ATTRIBUTE_LIST = ByLevelColor, ByLevelStyle, ByLevelWeight,OverrideSymbology, OverrideColor, OverrideStyle, OverrideWeight, OverrideMaterial, ByLevelMaterial, GlobalDisplay, GlobalFreeze, DisplayPriority, Transparency, Lock # Controls the list of Level-attributes that can be edited
HTH
Ian