Shadows On Translucency

Hi All, can somebody shed some light on what is happening in the video?

The top and bottom planes are both opaque and the middle one is translucent. All shadows work at distance but I simply can’t get close up to the shadow cast onto the translucent surface. I believe this shadow is a contact shadow, which is the only type I can get working.

The only light in the scene is a point light and everything is set to moveable/dynamic (the way i need it). I have checked the bounds scale but increasing that didn’t do anything.