SQLAlchemy diagram only shows one (base) model

I'm writing a Flask app using Flask-SQLAlchemy.

When I try to view a SQLALchemy diagram it only shows one box for the base database model I created that all other models inherit from.

I have the app structured as such:

package/
    __init__.py # app factory, imports db, inits db in app factory
    database/
        __init__.py # db = SQLAlchemy()
        models.py

Inside models.py I am importing db from the database package and have a base class defined as BaseModel(db.Model) which all of my actual models inherit from.

When I try to view a SQLAlchemy dependency diagram I only get a box that shows the package.database.models.BaseModel object.

I remember this working once, but that was BEFORE I switched all my models away from inheriting directly from db.Model and instead used the new BaseModel.