Calling Python function making use of numpy results in strange behavior

I have a tiny Python function which simply prints the installed numpy version. I call this function from Matlab. I have Python 3.7.4 (Anaconda) and Matlab R2020a.

Python code (python_module.py) looks like this.

import numpy as np

def print_numpy_version():
    print('Numpy version is {}'.format(np.__version__))
    return

If I call the print_numpy_version function from Matlab as shown below then everything works fine. I see the numpy version printed in Matlab command window. (My Python virtual environment is named opencv-env.)

close all;clear;clc;

setenv('PATH',[getenv('PATH'),'C:\Anaconda3\envs\opencv-env\Library\bin;']);
py.python_module.print_numpy_version();

However, if I try to call print_numpy_version from Matlab as shown below then I get an error.

close all;clear;clc;

try_this();

function try_this()

setenv('PATH',[getenv('PATH'),'C:\Anaconda3\envs\opencv-env\Library\bin;']);
py.python_module.print_numpy_version();

end

Error message is:

Unable to resolve the name py.python_module.print_numpy_version.

Error in main>try_this (line 10)

py.python_module.print_numpy_version();

Error in main (line 5)

try_this();

This is very strange. The only difference between the working Matlab code and the failing one is that in the latter I am calling Python function from within a Matlab function. Furthermore, this failure only happens with numpy. If I try to print the version of another Python package (say opencv) then Matlab code works fine in both cases.

Any idea what's causing this starnge behavior?