ID 394524 - Other channels will not have an Alpha within the Monitor window - changes Overlay behaviour

Problem summary
Katana3.1 appears to have removed the alpha background on 'other' channels created by Renderman and 3Delight.

Within Katana3.0 and earlier, if a user Preview Renders a project with custom AOV layers, the custom channels will have a White background:
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Running the same script in Katana3.1 will display no Alpha:
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The problem above becomes an issue when a user decides to use the Overlay/Underlay monitor feature, as it will display different results.

This issue does not occur in Arnold, as they have set up an Alpha layer of the object to be used:
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Also Note: Renderman and 3Delight do not Disk Render the Alpha, Arnold does.


Customer reported version
katana.3.1v4

Customer reported platform
rhel7

Steps to reproduce

1) Open a simple project with a Primitive, Camera, Material and a GafferThree.

2) Setup a diffuse AOV layer for the renderer ( will be different for each renderer )

3) Preview Render the project

4) Switch the channel in the Monitor to the diffuse and also display the alpha

Result: Katana3.1 will be black with no alpha, Katana3.0 and earlier will have a white background.

Expected behaviour
The background should be White, so users can review the Overlay/Underlay

Actual behaviour
There is no longer an Alpha.

Workaround
Unknown.

Reproduced by support

This bug has been reproduced in:
Katana3.1v1 - Windows 7 - CentOS7
Katana3.1v1 - Windows 7 - CentOS7 - regression


Unable to reproduce bug in:
Katana3.0v9 - Windows 7 - CentOS7

Earliest version tested
- This issue no longer appears in this version and has regressed