UE5 Preview 1 - Transluscent materials not behaving as expected

glass material issues ,
the default (starter content glass material ) has its ior value set to 1.4 maybe great for a vase or other glass object ,
but when used as a window , looking at it almost side on gives reflections from behind it ,

lighting issues , light though glass if a single plane is used gives incorrect illumination , using a 3d mesh (2 sides with a small thickness distance between them gives much better results )
although it still gives incorrect shadowing on the ground , that is relative to the external global light source position ,
as much as i have tried i have had no luck in getting the light through the windows to give the correct shadws on the ground , ho btw i get the same results with hardware raytracing on or off with lumin



above all with ior(refaction) set to 1

with default refaction of 1.4…

vers refaction of 1


although it dose not solve the shadow transparancy issue it does resolve the refection issues