ID 485863 - Edge Chamfer creates holes when using mitering on border edges

Problem summary
Edge Chamfer creates holes when using mitering on border edges

Customer reported version
modo.15.1v1

Customer reported platform
windows10

Steps to reproduce

1) Open Modo

2) Create a Cube with 4x4x4 segments

3) Delete as cluster of faces from part of the cube:

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4) Select the edge of the hole, then Edge>Edge Chamfer

5) Drag the Viewport to increase the Offset size, this works correctly:
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6) Increase the Mitering Offset, holes start appearing in the mesh:

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Expected behaviour
For the edges to be mitered correctly, in this case, nothing to change

Actual behaviour
Holes will appear when increasing the mitering offset

Workaround
Unknown.

Reproduced by support
This bug has been reproduced in:
Modo 15.1v1 - Windows 10, macOS BigSur - regression

Unable to reproduce bug in:
Modo 15.0v3 - Windows 10, macOS BigSur

Earliest version tested
Modo 15.0v3 - This issue doesn't appear in this version and has regressed