ID 248914 - masking_mode knob in the Viewer node doesn't effect the Viewer panel

Problem summary
masking_mode knob in the Viewer node doesn't effect the Viewer panel result.

Customer reported version
nuke.10.5v1

Customer reported platform
windows10

Steps to reproduce

1) Open Nuke

2) Create a Checkerboard node and view it

3) Right click in the Viewer and select the Viewer Settings option

4) Change the mask mode knob, it won't effect the Viewer. Checking the masking_ratio control on the Viewer panel, the option has changed, but it doesn't take effect, as show below:

​

Reproduced by support
This problem has been reproduced on:
Nuke 10.5v1 - Windows 10 - CentOS 6.8 
Nuke 10.0v5 - Windows 10
Nuke 10.0v1 - Windows 10
Nuke 9.0v9 - Windows 10
Nuke 9.0v1 - Windows 10 - CentOS 6.8 

This was not an issue in:
Nuke 8.0v6 - Windows 10 - CentOS 6.8

Expected behaviour
For the Viewer panel to reflect the changes in the Viewer node

Actual behaviour
It didn't