How to add/modify private registry keys for Visual Studio 2019?

Question

Based on this answer, I added keys to Visual Studio 2017 and it worked just fine. But it doesn't work for Visual Studio 2019.

Here's what I do:

1. I create a new project, using VSIX project template
2. I add a .pkgdef file to it, and I populate it using these lines: [$RootKey$\TeamFoundation\SourceControl\Checkin Policies] "ExampleKey"="ExampleValue"
3. I modify source.extension.vsixmanifest file and add assemblies and packages to it (based on that answer, and just like VS2017)
4. I make sure my extension is unsintalled (VS2019 => Extension => Manage Extensions => Selecting my extension => Uninstall => Closing VS2019)
5. Then I make sure the ExampleKey ExampleValue is not present in privateregistry.bin. (Opening regedit.exe, selecting HKEY_LOCAL_MACHINE => File => Load hive => %localappdata%\Microsoft\VisualStudio\16.0_e880ebae\privateregistry.bin as VS2019Registry, then selecting VS2019Registry\Software\Microsoft\VisualStudio\16.0_e880ebae_Config\TeamFoundation\SourceControl\Checkin Policies)
6. Then I unload the VS2019Registry hive.
7. Then I double click my extension, and install it on VS2019
8. Then I open VS2019 to make sure my extension is installed, and it's in the list of extensions.
9. Then I close VS2019, and reopen private registry, but my key is not added to the intended path.

What should I do? How can I debug it? The exact same path was working for VS2017.