XUnit 2.1 Custom CategoryTraitAttribute is ignored in Unit Test Explorer - Group by

[psech]

Details:
VS: 2015 Professional Update 3
R#: 10.0.2 Ultimate
Xunit: 2.1.0

The issue:
I have got custom attribute like

public class SmokeTestAttribute : CategoryTraitAttribute
{
    public SmokeTestAttribute() : base("Smoke") { }
}

and I am using it as

[Fact(DisplayName = "User should be able to login")]
[SmokeTest]
public void UserShouldSignIn()

When I am selecting Group by: Category in R# Unit Test Explorer I see all of the tests as <Uncategorised> (xx tests).
However, in VS Test Explorer I can see Category [Smoke] (xx) and No Traits (yy)

[psech]

Any update on this?

[drewnoakes]

Seems related to #35 and #27.