Projection file disappears in WPF project

[mmarczell-graphisoft]

Describe the bug
I would like to use CsWinRT in WPF the same way I use it in a WinUI project, but it doesn't build.

To Reproduce
See my minimal repro at https://github.com/mmarczell-graphisoft/winrtbug

1. Build and run the WinUI project. It builds and runs.
2. Build the WPF project. It fails to build.

Expected behavior
The WPF project should also build and run.

Actual behavior
As long as I do not have the using directive in my WPF C# code, nor any code using those definitions, the C# projection file does get generated under obj\Debug\net6.0-windows\Generated Files\CsWinRT. However as soon as I enter the using directive and rebuild, this file is no longer there.

Version Info
CsWinRT 2.0.7
net6.0-windows

[mmarczell-graphisoft]

@smourier has provided a workaround which can be seen here:
https://stackoverflow.com/questions/78316887/use-c-winrt-component-but-really-any-winrt-component-in-wpf-net-6/78342481#78342481

or here:
mmarczell-graphisoft/winrtbug@e417f57

but this is only a workaround, the bug still stands.

[mmarczell-graphisoft]

Looking at cswinrt.rsp (which is a file that contains the command line arguments), I can observe that as long as my C# code does not contain using winrtcomponent_cpp;, the rsp file contains

-input "C:\Dev\git\winrtbug\_build\x64\Debug\winrtcomponent.cpp\bin\winrtcomponent.cpp\winrtcomponent_cpp.winmd"

but if I enter the using directive, that line in the rsp becomes empty.

- input