InternalsVisibleTo PublicKey does not respect variables in NET5 Preview SDK

I’m hoping this is the right place, please let me know If I shouldraise the issue elsewhere.

For SDK versions prior to .NET 5 previews it is possible to declare InternalsVisibleTo values in a Directory.Build.props file in subfolders using the following approach.

<InternalsVisibleTo Include="SixLabors.ImageSharp.Web.Tests"  PublicKey="$(SixLaborsPublicKey)" />

Where the variable had been declared in a root Directory.Build.props file.

<SixLaborsPublicKey> KEY HERE </SixLaborsPublicKey>

When attempting to build a solution via dotnet build with any .NET 5 preview SDK installed the folllowing error occurs.

error CS1726: Friend assembly reference 'SixLabors.ImageSharp.Web.Tests' is invalid. Strong-name signed assemblies must specify a public key in their InternalsVisibleTo declarations.

What has changed which breaks current behavior and what (other than disabling the preview via global.json) is the correct workaround?

[KalleOlaviNiemitalo]

@ladeak, this fix is not in https://github.com/dotnet/sdk/blob/release/7.0.1xx-preview5/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.GenerateAssemblyInfo.targets, but it is in https://github.com/dotnet/sdk/blob/release/7.0.1xx-preview6/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.GenerateAssemblyInfo.targets:

https://github.com/dotnet/sdk/blob/18c815b323b4ea40db52788c146de9b2c89c9baf/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.GenerateAssemblyInfo.targets#L109-L111

[tannergooding]

The SDK version does support PublicKey as well, but as a global property, rather than as metadata attached to an individual IVT: https://github.com/dotnet/sdk/blob/master/src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.GenerateAssemblyInfo.targets#L108-L112