cx_freeze creating exe but encountering: zipimport.ZipImportError: can't find module 'mainprogram__main__' when running it

Question

I have a repository structure as such:

MinimalExample
├── _buildscripts
│   ├── setup.py
│
├── _MainProgram
│   ├──_modules1
│   │  ├──timescalculation.py
│   │
│