ID 369395 - Advanced Viewport mixes colors and effects areas incorrectly when a group-masked Unity Albedo layer is used

Problem summary
Advanced Viewport mixes colors and effects areas incorrectly when a group-masked Unity Albedo layer is used. 

Customer reported version
Modo 12.1v1 

Customer reported platform
Windows 10 

Steps to reproduce

1) Open the attached scene. 

2) Change viewport display to Advanced.  

3) Open the Preview Render by pressing "F8" or go to Render->Open Preview.

4) Go to the Shading Tab. Under the material group "Group", make sure the items highlighted in red are enabled (please see the image below). The incorrect colour in the Advanced Viewport should not match with the correct colour seen in the Preview Render.

Workaround
Unknown workaround. 

Reproduced by support

This bug has been reproduced in:
Modo 12.1v2 - Windows 10 - CentOS 7 - MacOSX 11.13 
Modo 12.0v1 - Windows 10
Modo 11.2v3 - Windows 10
Modo 11.1v1 - Windows 10
Modo 11.0v3 - Windows 10
Modo 10.2v4 - Windows 10 - CentOS 7 - MacOSX 11.13 

Earliest version tested
Modo 10.2v4 - This issue seems to appear in all versions of Modo. 

Expected behaviour
Groups Masks should render Unity Albedo layers in the Advanced Viewport identical as in the Preview Render. 

Actual behaviour
Group-masked Unity Albedo layers in the Advanced Viewport is inconsistent with the Preview Render.