Problem trying to do DG with complex spaces

I’m trying to to DG (following 2.8 Discontinuous Galerkin Methods — NGS-Py 6.2.2302-87-ga5a5eff3b documentation) but for a Helmholtz problem. Since some of my stabilization terms will be complex, I set the complex=True flag for the DG space. Unfortunately, this results in the error message:

netgen.libngpy._meshing.NgException: FacetLinearFormIntegrator::CalcFacetVector not implemented!in Assemble LinearForm

Am I doing something wrong or is this just something not yet implemented in NGSolve?

They are added on the current master.