ID 431602 - The background remains black when specific settings are used in the ZDefocus node

Problem summary
The background remains black when specific settings are used in the ZDefocus node.

Customer reported version
nuke.12.0v3

Customer reported platform
windows10

Steps to reproduce

1) In Nuke, create a Checkerboard node and a ZDefocus node downstream.

2) View the ZDefocus node and open the Properties bin.

3) Set the following values for the knobs: 

Expected behavior
The image should appear with the correct settings.

Actual behavior
The image appears black.

Workaround
There is no available workaround at this time.

Reproduced by Support

Nuke 13.0v4 - Windows 10

Nuke 13.0v1 - Windows 10

Nuke 12.1v1 - Windows 10

Nuke 12.0v1 - Windows 10

Nuke 11.0v1 - Windows 10

Nuke 10.0v1 - Windows 10

Unable to reproduce bug in:
Nuke 9.0v9 - Windows 10

Earliest version tested
Nuke 9.0v9 - This issue doesn't appear in this version and has regressed