Cannot create app packages for projects containing source generators

_This issue has been moved from [a ticket on Developer Community](https://developercommunity.visualstudio.com/t/Cannot-create-app-packages-for-projects-/10770385)._

---
Attempting to create app packages for a WPF project containing a source generator throws an error, as if the source generator is not running.

I have tried rolling back the .NET SDK to no avail.

Download repro project:
(attached or via link [https://github.com/user-attachments/files/15571552/CsWin32WaprojDeployRepro.zip](https://github.com/user-attachments/files/15571552/CsWin32WaprojDeployRepro.zip))

1. Select the packaging project

2. Project > Publish > Create app packages

3. Complete the wizard (Sideloading > Skip signing > x86 + x64 + arm64 > Installer URI [https://example.org](https://example.org) > Create)

4. Observe error in Error List / Output window (screenshot attached):

```
The name ‘Windows’ does not exist in the current context […]
X:\CsWin32DeployRepro\WpfApp\MainWindow.xaml.cs
```

---
### Original Comments

#### Feedback Bot on 10/17/2024, 08:29 AM:

We have directed your feedback to the appropriate engineering team for further evaluation. The team will review the feedback and notify you about the next steps.