vray proxies not visible when using multiple shading groups

[Koshi]

title tells it all...

when I create a proxy out of maya with multiple shaders assigned (multiple shading groups) the proxy doesn't display in the viewport.

it works perfectly during rendering and even creates the different shading groups correctly, but viewport display
seems to be not working.

[Koshi]

When I group this object under another one in the scene it gets visible again...