Using an SDK that comes from a PackageReference in a WPF application is broken

[dotMorten]

• .NET Core Version: 3.0preview 7 + 3.0rc1
• Windows version: Several Win10 versions and Win11 (ie doesn't matter)
• Does the bug reproduce also in WPF for .NET Framework 4.8?: No
• Is this bug related specifically to tooling in Visual Studio (e.g. XAML Designer, Code editing, etc...)? If yes, please file the issue via the instructions here.
  No? It is introduced with .NET 6 and/or VS2022 installer, but will even affect VS2019/.NET5 installs once installed

Problem description:
Using an SDK that comes from a PackageReference (MSBuild.Sdk.Extras) in a WPF application is broken with WPF PackageReference support enabled.
Setting IncludePackageReferencesDuringMarkupCompilation to false works around the issue (but comes with other downsides).
On a PC that only has VS2019 installed, the problem doesn't reproduce. If you install VS2022p3.1, the problem does reproduce, even from a VS2019 command prompt.
The problem seems to occur just by installing the .NET 6 SDK, and will break even .NET 5 and .NET Framework builds.

Actual behavior:

error MSB4236: The SDK 'MSBuild.Sdk.Extras/3.0.23' specified could not be found.

Expected behavior:
Build completes.

Minimal repro:
From a VS2019 or VS2022 prompt run:

    git clone https://github.com/Esri/arcgis-toolkit-dotnet
    cd arcgis-toolkit-dotnet\src\Toolkit\Toolkit
    msbuild /restore /t:Build Esri.ArcGISRuntime.Toolkit.csproj

[dotMorten]

@ryalanms This is related to .NET 6.0. This is a showstopper as we have no way to build things and target .NET 6 now. Is there a reason this is scheduled for 7.0?
Or could we at least get a workaround?

[ThomasGoulet73]

@dotMorten I just opened #5426 which fixes the build of arcgis-toolkit-dotnet for me. Could you try it and see if it fixes yours ?

I opened it in main (aka .Net 7) but maybe the WPF team would like to backport it to .Net 6.

[dotMorten]

@ThomasGoulet73 You're a rock star!