Weird distortion when rendering character through window. (Solved)

BlueFingers

I have the weirdest issue making a scene, in the texture shaded viewport it looks like this:

In Iray preview (and also when rendering) it looks like this:

 

How can I solve this weird distortion?

I abbandoned the scene as other things weren't working out either, but I'd still like to understand the issue.

Matt_Castle

Turn on Thin Walled on the window. It's got a front face, but no back face, so didn't know where to stop the glass. (Or you can add a back face with matching surface parameters - it doesn't need to be the same object, it just has to match parameters).

BlueFingers

That did the trick!! I never knew this! How weird.

Thank you so  much Matt!!!