pip cannot import Cython but python setup.py install can

I am writing a Cython module. I have Cython installed. The start of my setup.py file is as follows:

import os
from distutils.command.build_ext import build_ext
from typing import Callable

from setuptools import setup, Extension

from Cython.Build import cythonize

When I run pip install ., I end up with the following error:

  ModuleNotFoundError: No module named 'Cython'

However, if I run python setup.py install, everything works as expected.

I have ran pip install Cython --upgrade.

Python version: 3.7.10

Cython version: 0.29.23

pip version: 21.0.1

I am certain that more information will be needed, but not sure what I should provide.

Edit:

Python path: /Users/petioptrv/miniconda3/envs/ib-insync-sim-test/bin/python

pip path: /Users/petioptrv/miniconda3/envs/ib-insync-sim-test/bin/pip

As evident by the path, I use conda to manage my environment.