ResolveAssemblyReference cannot find dll and I cannot force it to look where it is

Question

I have solution with n csharp projects and cpp project on top, this cpp provides interfaces and headers so those csharp ones can be used in other cpp solutions.

The build machine is configured to build csharp project with anyCPU architecture so it provides single assembly per build in Solution\bin\Release. For cpp the anyCpu is not available so I build project twice and store assemblies in Solution\bin\Release\x86 and x64 folders.

This is all to get it packaged in nuget as a single package with .targets file to ease consumption in other cpp projects.

Issue is that cpp project is looking for csharp asseblies using ResolveAssemblyReference and cannot find it, giving missleading message:

    ResolveAssemblyReferences:
    Primary reference "Implementation".
        Could not find dependent files. Expected file "C:\Jenkins\Workspace\Solution\bin\Release\x86\Implementation.dll" does not exist.
        Could not find dependent files. Expected file "C:\Jenkins\Workspace\Solution\bin\Release\x86\Implementation.dll" does not exist.
        Resolved file path is "C:\Jenkins\Workspace\Solution\bin\Release\x86\Implementation.dll".
        Reference found at search path location "".

I tried to alternate ResolveAssemblyReferences behaviour using command line properties, custom targets/properties, but without any luck. The parameters described in https://learn.microsoft.com/en-us/visualstudio/msbuild/resolveassemblyreference-task?view=vs-2017 seem to be computed during the build process and I cannot inject any value, which should be in this case something like $(OutDir)..

The one feasable solution seems to be copy c# dlls into each cpp folder, but I dont think it is the way to solve it properly.

Closes I got is by using /p:ReferencePath like below:

"C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\MsBuild\15.0\bin\MsBuild.exe" /p:BuildProjectReferences=false /p:Configuration=Release /p:DebugType=full /p:DebugSymbols=true /p:PlatformToolset=v120 /p:WindowsTargetPlatformVersion=8.1 /p:ForceImportBeforeCppTargets="C:\Jenkins\Workspace\Solution\Cpp.props" /p:OutDir="C:\Jenkins\Workspace\Solution\bin\Release\x86\" /p:Platform=Win32 /t:Build Interface\Interface.vcxproj /p:ReferencePath="C:\jenkins\workspace\Solution\bin\Release"

My custom Cpp.props does:

<Target Name="Output" BeforeTargets="ResolveAssemblyReferences">
  <Message Text="AssemblySearchPaths: $(AssemblySearchPaths)" />
</Target>

and by adding /p:ReferencePath it got added to AssemblySearchPaths as second record, after {CandidateAssemblyFiles}; but it is still not finding those dlls