Hi, as far as I know that is expected behavior. To get what you want, you could check whether using PointOfViewBackwardOffset and NearClippingRadius in the sight sense config are enough to do what you want (it should give you close awareness but maybe not the green periperal vision).
would an acceptable workaround be to create a child AI_Sight_Config class and use that?
I never tried that, so I do not know whether it will work.
If you use C++, then you could also consider implementing the CanBeSeenFrom function of the IAISightTargetInterface inside the actors you want to be seen by the AI. There you can then set the stimulus strength which by default is always 1.0 in the sight sense (e.g. change the stimulus strength based on dot product and distance)