scipy import from module fails, sometimes (path-dependent)

Question

I open a live Python repo (https://petrkryslucsd.github.io/pystran.live/lab/index.html?path=Welcome.ipynb). I click through to the folder pystran/tutorials. I create a notebook (Pyodide) with a single cell

import context
from pystran import model

Execution fails with

---------------------------------------------------------------------------
ModuleNotFoundError Traceback (most recent call last)
Cell In[2], line 2
 1 import context
----> 2 from pystran import model
File /drive/pystran/pystran/__init__.py:81
 65 __all__ = [
 66 "gauss",
 67 "model",
 (...) 77 "Abaqus_import"
 78 ]
 80 # Import the submodules
---> 81 from . import model
 82 from . import section
 83 from . import rotation
File /drive/pystran/pystran/model.py:7
 5 from math import sqrt, pi
 6 from numpy import array, zeros, dot, mean, concatenate, float64, int32, inf
----> 7 import scipy
 8 from scipy.linalg import solve, eigh
 9 from collections import namedtuple
ModuleNotFoundError: No module named 'scipy'

But if I put into the cell

import context
import scipy
from pystran import model

it executes without an error.

Also, when I open an existing notebook, the very same import of context and from pystran import model works fine.

I don't understand why that is?