There may be a bug when running the HyperDAG backend on the HPCG algorithm until convergence.
The corresponding hyperDAG output file was incorrect in the initial commit of the hyperDAG DB at https://github.com/Algebraic-Programming/HyperDAG_DB; the file was located at extracted/alp-graphblas/until_convergence/hpcg.txt.
Specifically, the line describing vertex #13916 was missing entirely from the file.