ID 371960 - Maintain Co-Planar Edges option does not fix holes when using the Bevel Edge tool

Problem summary
When using the Maintain Co-Planar Edges" tool one or multiple holes appear around a bevelled edge. This options should fix co-planar edge errors but instead results in poorer bevel edge performance. 

Customer reported version
Modo 12.1v2

Customer reported platform
Windows 10 

Steps to reproduce

1) Create a cube and then select an edge for bevelling. 

2) In the Model View, click on Edge -> Bevel. In the Edge Bevel Properties, change Edge Shape to "Round".

3) Increase Round Level to 3. Start bevelling the edge on the cube. 

4) Select another edge and reset Round Level to 0 and bevel again. Now there are one or more holes appearing around the bevelled edge.

5) Enable "Maintain Co-Planar Edges". With this option enabled, the hole does not disappear in the example image below. 

Workaround

A Mesh Fusion workflow can be used to maintain good edge flow and avoid creation of holes around outer edges:

1) Create a new scene. Go to the Model view and then go to the "Fusion" tab. 

2) Under "Fusion Meshes", select "Qbic Geometry" and create a cube and a sphere to utilise with Mesh Fusion.

3) Left-Click while holding down "Alt" and then under "Select Mesh Role & Apply" select the cube as "Primary" mesh to trim with other meshes. 

4) Select the sphere and assign it as a "Subtractive Trim" mesh. 

5) A "Mesh Fusion" item has now been created. Select this item and open its Properties. 

6) In the Properties tab, use the default "Strip" and "Corner" settings. Modify these settings if desired. 

7) Select the cube and the sphere. In the Fusion tab under "Trim/Un-Trim", select "Trim". 

8) Back in the "Mesh Fusion" Properties, change the Mesh Mode to "Airtight Final". 

9) Under Output Mesh with the "Mesh Fusion" item selected, use "Convert to Mesh Item".

10) The converted mesh item should now have improved edge flow without any holes. 

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Reproduced by support

This bug has been reproduced in:

Modo 12.1v2 - Windows 10 - CentOS 7 

Modo 12.0v1 - Windows 10

Modo 11.2v3 - Windows 10 - CentOS 7 

Earliest version tested
Modo 11.2v3 - This feature did not exist before this version

Expected behaviour
The "Maintain Co-Planar Edges" option should merge together unselected co-planar edges with the next unselected sharp edge. 

Actual behaviour
Holes appear when using the "Maintain Co-Planar Edges" option.