HED returns 0

Created by: computerquest

I have a bunch of graphs I know to be unique, and when I calculate GED using GraphEditDistance it returns non-zero values as expected. However when using HED instead of GraphEditDistance, it outputs only 0.

ged = gm.HED(1, 1, 1, 1) 
result = ged.compare(all_graph, None)
print(*result)

Is my code wrong or is there an issue with the library?