ID 419264 - Changing the Spot Radius parameter on 3Delight lights creates a hidden square that casts a shadow

Changing the Spot Radius parameter on 3Delight lights creates a hidden square that casts a shadow

Problem summary
When using a 3Delight "Spot Light", changing the "Spot Radius" parameter in the GafferThree -> Object tab to a '1' will cause a shadow to appear. Setting the "Visible to Camera" parameter to true will show a black square that seems to be the cause. 
Note) A similar issue occurs with the 3Delight "Point Light" when you change the "Radius" parameter.

Customer reported version
Katana.3.2v1

Customer reported platform
Windows 10

Steps to reproduce

1) Make a basic scene: Create a CameraCreate node and add a plane with the PrimitiveCreate node

2) Create a "dl3DelightMaterial" surface shader material using a Material node and assign it to the plane using a MaterialAssign node. 

3) Create a GafferThree node and add a 3Delight "Sky Light" and a 3Delight "Spot Light"

4) Reposition the spotLight so that it is about 1 unit above the plane.

5) Within the GafferThree parameters tab, select the spotLight and change the "Spot Radius" parameter to a '1' in the Object tabs below.

6) Start a Preview Render from the GafferThree node.

Result) An invisible square on the spotLight causes a shadow to be cast from the skyLight onto the plane.
Note) Within the Object tabs, setting the "Visible to Camera" parameter to true will reveal a black square on the spotLight that appears to be the cause of the shadow.

Expected behaviour
Lights do not have hidden geometry that other lights can cause to cast a shadow.

Actual behaviour
Changing the "Spot Radius" parameter produces an invisible square that can cast a shadow.

Workaround
Unknown.

Reproduced by support
This bug has been reproduced in:
Katana 3.2v3 - Windows 10
Katana 3.2v1 - Windows 10 - CentOs 7
Katana 3.1v7 - Windows 10
Katana 3.1v1 - Windows 10
Katana 3.0v1 - Windows 10