Intellisense works only when the module folder is in current workspace

I made a module recently, for data management. Then I decided to split it into several submodules. However, when I import the module, the auto-complete doesn't work, even though the module itself works perfectly. I found out, that if I keep the module in my workspace, the auto-complete works.

Sample import: from module.core.client import Client

The structure of my module directory:

module
  module
    core
      __init__.py
      client.py
    extra
      __init__.py
      municipality.py
    modules
      __init__.py
      generic.py
      timetable.py
    __init__.py
    utils.py
  ...
  setup.py

If there's any issue with my module set-up, please let me know.

Thank you.