azure-functions-core-tools: Unable to publish Facebook Prophet despite publishing all dependencies.

I am using Facebook’s prophet module to do some predicting using a Function app. When I attempt to publish my app, i get the following error:

Installing collected packages: asn1crypto, azure-common, azure-nspkg, azure-cosmosdb-nspkg, idna, certifi, chardet, urllib3, requests, six, python-dateutil, pycparser, cffi, cryptography, azure-storage-common, azure-cosmosdb-table, ephem, pytz, convertdate, cycler, Cython, redis, holidays, setuptools, kiwisolver, lunardate, pyparsing, numpy, matplotlib, pandas, pip, azure-storage-queue, pystan, setuptools-git, fbprophet
  Running setup.py install for fbprophet ... error
    Complete output from command /usr/local/bin/python -u -c "import setuptools, tokenize;__file__='/tmp/pip-install-hjtmj53k/fbprophet/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" install --record /tmp/pip-record-kq9a4bm4/install-record.txt --single-version-externally-managed --compile --home=/tmp/pip-target-w6b7hjux:
    running install
    running build
    running build_py
    creating build
    creating build/lib
    creating build/lib/fbprophet
    creating build/lib/fbprophet/stan_model
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/tmp/pip-install-hjtmj53k/fbprophet/setup.py", line 120, in <module>
        """
      File "/usr/local/lib/python3.6/site-packages/setuptools/__init__.py", line 145, in setup
        return distutils.core.setup(**attrs)
      File "/usr/local/lib/python3.6/distutils/core.py", line 148, in setup
        dist.run_commands()
      File "/usr/local/lib/python3.6/distutils/dist.py", line 955, in run_commands
        self.run_command(cmd)
      File "/usr/local/lib/python3.6/distutils/dist.py", line 974, in run_command
        cmd_obj.run()
      File "/usr/local/lib/python3.6/site-packages/setuptools/command/install.py", line 61, in run
        return orig.install.run(self)
      File "/usr/local/lib/python3.6/distutils/command/install.py", line 545, in run
        self.run_command('build')
      File "/usr/local/lib/python3.6/distutils/cmd.py", line 313, in run_command
        self.distribution.run_command(command)
      File "/usr/local/lib/python3.6/distutils/dist.py", line 974, in run_command
        cmd_obj.run()
      File "/usr/local/lib/python3.6/distutils/command/build.py", line 135, in run
        self.run_command(cmd_name)
      File "/usr/local/lib/python3.6/distutils/cmd.py", line 313, in run_command
        self.distribution.run_command(command)
      File "/usr/local/lib/python3.6/distutils/dist.py", line 974, in run_command
        cmd_obj.run()
      File "/tmp/pip-install-hjtmj53k/fbprophet/setup.py", line 44, in run
        build_stan_model(target_dir)
      File "/tmp/pip-install-hjtmj53k/fbprophet/setup.py", line 27, in build_stan_model
        from pystan import StanModel
    ModuleNotFoundError: No module named 'pystan'

when using func pack --build-native-deps. However, commenting out the fbprophet requirement, I am able to publish even though pystan is still on my requirements.txt.

My requirements file: requirements.txt

My thought may be that prophet is searching in wrong directories when the publishing process calls on its setup.py, however, installing using pip works fine on my local machine. Thanks!