ID 521698 - After saving and reopening a project, some clip metadata will not be accessible via Python

Problem summary
After saving and reopening a project, some clip metadata will not be accessible via Python. 
However, the metadata which cannot be accessed via Python is still displayed in the metadata view.
 
This issue has only been reproduced on Windows and Linux.
 
Customer reported version
Nuke 13.2v4
 
Customer reported platform
CentOS 7
 
Steps to reproduce
 
1) Open Nuke Studio.
 
2) Import the attached file.
 
3) Execute the following line of code in the Script Editor and note the result:

print(len(hiero.core.projects()[-1].clipsBin().items()[0].activeItem().mediaSource().metadata().keys()))

 
4) Save the project and close Nuke Studio.
 
5) Reopen Nuke Studio and reopen the project.
 
6) Execute the following line of code in the Script Editor:

print(len(hiero.core.projects()[-1].clipsBin().items()[0].activeItem().mediaSource().metadata().keys()))

 
Expected behaviour
All of the clip's metadata should always be accessible via Python.
 
Actual behaviour
After saving and reopening the project, some of the clip metadata is no longer accessible via Python.
 
Workaround
Unknown. 
 
Reproduced by support
This bug has been reproduced in:
Nuke Studio 13.2v4 - Windows 10 - Linux CentOS 7  
Nuke Studio 12.0v1 - Windows 10 - Linux CentOS 7
 
Unable to reproduce bug in:
Nuke Studio 13.2v4 - macOS 11.6 (Big Sur)
Nuke Studio 9.0v1 - Windows 10
 
Earliest version tested
Nuke Studio 9.0v1
- This issue doesn't appear in this version and has regressed