For *.proj files, GlobalPackageReferences are not picked up.

Repro

Foo.proj:

<Project Sdk="Microsoft.Build.NoTargets/3.6.0">
  <PropertyGroup>
    <TargetFramework>netstandard2.0</TargetFramework>
    <ManagePackageVersionsCentrally>true</ManagePackageVersionsCentrally>
  </PropertyGroup>
  <ItemGroup>
    <Artifact Include="$(MSBuildThisFile)">
      <DestinationFolder>$(BaseOutputPath)</DestinationFolder>
    </Artifact>
  </ItemGroup>
</Project>

Directory.Packages.props:

<Project>
  <ItemGroup>
    <GlobalPackageReference Include="Microsoft.Build.Artifacts" Version="4.1.0" />
  </ItemGroup>
</Project>

Run msbuild /restore and notice that bin\Debug\netstandard2.0\Foo.proj does not exist despite the Artifact item.

Analysis

Looking at binlogs, the issue seems to be that there is a Microsoft.Managed.DesignTime.targets which overrides the CollectPackageReferences target, which is the target which handles GlobalPackageReferences.

Note that if the project extension is .csproj instead, it will actually work due to the import ordering being different.

Import order for proj file:

Import order for csproj file: