VisualD/Visual Studio Cannot Open Premake Generated .visualdproj

I've been trying out premake with D, and have found that Visual Studio cannot open the generated visualdproj files. Even the example given in the readme for the module does not work. However, a C project appears to work just fine even in the same solution. What is happening here?

This is my premake5.lua:

workspace "Test"
    configurations { "release", "debug" }

    project "app"
        language "D"
        kind "ConsoleApp"
        files "source/app.d"

    project "app2"
        language "C"
        kind "ConsoleApp"
        files "source2/app.c"