Interior mode issue with KS7

[BJT_DAVE]

What is the difference between interior mode in KS6 and KS7? We have had problems with glass using interior mode in KS7 where it acts like a mask and doesn't render *(see previous post) and now when I raise a ground plane off the ground the shadow can be seen through the ground plane (second screenshot) whereas it wasnt visible in KS6 (1st screenshot). Anyone else have this problem or is it just us? As well as this, in KS6 when you looked at the underside of the ground plane it is black (3rd screenshot) and in KS7 it is transparent (4th screenshot) when raised off the ground...the exact opposite of how it should be??