roslyn: Find All References doesn't work in a netstandard2.0 / net47 project combination

Version Used: Visual Studio 15.5

Steps to Reproduce: I have a netstandard2.0 library and a net47 project referencing that library

// netstandard2.0 target framework, Microsoft.NET.Sdk
public interface IFoo { void Foo(); }
// net47 target framework, Microsoft.NET.Sdk.Web
interface IBar { void Bar(); }
class FooBar : IFoo, IBar
{
    public void Foo() { }
    public void Bar() { }
}

Now run Find All References on both Foo and Bar methods (or look at CodeLense)

Expected Behavior:

Both Foo() and Bar() should show references back and forth.

Actual Behavior:

Only Bar() from within the net47 project itself has a reference:

When I change the netstandard2.0 library to net47, the reference for Foo() shows up as expected