Namespace members not recognized when defined in together group?

Question

The following snippet is supposed to display in total four interface/class entities in nested namespaces

@startuml

namespace Outer {

        together {
                interface One
                interface Two
        }

        namespace Inner {
                class One
                class Two
        }

}

Outer.Inner.One --|> Outer.One
Outer.Inner.Two --|> Outer.Two

@enduml

The resulting class diagram displays six boxes: While interfaces Outer.One and Outer.Two are arranged as desired, they get ignored when drawing relation lines. Instead, an extra pair of classes Outer.One and Outer. Two are added as relation targets.