Reflecting glass behaviour

Hi everyone,

Can anybody explain why this glass behaves in such a way ? Please see the image attached. I am using V-Ray for Rhinoceros 6 3.60.02. Material is the standard Vray Glass_Window_WaterBlue. I want to achieve more or less the effect that you see on the right hand side of the image. Glass there seems to behave in a desired way. Glass on the right of the image is either to milky or when flipped its to transparent or moved forward starts to behave in a normal reflective way. I have only tweaked Reflection IOR of that material.
Thanx !

Moving glass to the front so it is not fitted in the frame led to a proper behavior, not sure why ?