This issue was originally brought up on Gremlin Users:
but in summary there is an issue with GraphTraversal._getattr which provides sugar for values(key). It works fine except that PyCharm debugger introspects by way of len which then calls values("len_") and alters the traversal. It is fixed with something like:
def __getattr__(self, key): if key == '__len__': raise AttributeError("nope") return self.values(key)
but I'm not sure if that's the best fix for this issue.