Create a model dependency diagram in Pycharm IDE using Google appengine

Question

I have an Appengine application that I recently imported into Pycharm's development environment.

I want to create diagrams of model dependence on it. However, every time I create a dependency diagram of the Google application engine, it simply returns a new empty window without any entities.

Creating a python class diagram works great.

Any thoughts on why PyCharm doesn't recognize the Google engine models that I have in my application?

many thanks

EDIT: I also tried creating a basic new application in PyCharm, and this also does not seem to work with creating a model dependency diagram. The problem seems to be related to PyCharm if someone doesn't have a working dependency diagram of the model created by PyCharm ??