ID 515081 - Applying a masking ratio to the Viewer clears the Playback Cache.

Problem summary
Applying a masking ratio to the Viewer clears the Playback Cache.
 
Customer reported version
Nuke 13.1v2
 
Customer reported platform
Windows 10
 
Steps to reproduce
 
1) Open Nuke.
 
2) Create a CheckerBoard node, and attach it to the Viewer.
 
3) Press the Play button in the Viewer, to cache some frames.
 
4) Open the masking_ratio dropdown menu and select a different option:
 

 
Expected behaviour
Applying a masking ratio on the Viewer should not clear the cache. 
 
Actual behaviour
Applying a masking ratio to the Viewer clears the Playback Cache.
 
Workaround
Unknown.
 
Reproduced by support
This bug has been reproduced in:
Nuke 13.2v3 - Windows 10 - Linux CentOS 7 - macOS 10.15 (Catalina)
Nuke 12.0v1 - Windows 10 - Linux CentOS 7 - macOS 10.15 (Catalina)
Nuke 9.0v1 - Windows 10
 
Earliest version tested
Nuke 9.0v1
- This issue appears to be in all tested versions of the product