I found this question which is very similar to the behavior I am experiencing – however I cannot make use of the answers offered, so I am repeating the issue here.

I have installed Emacs 29.3 on my Windows11 OS and Python through an Anaconda installation.

Launching python.exe from a cmd windows shell and inputting:

import matplotlib.pyplot as plt
plt.plot([1,2,3,4])
plt.show()

I get the output I would expect, i.e. a plot window.

From within Emacs, I have updated the python-shell-interpreter variable to contain the path to python.exe, so after starting python-mode I can C-c C-p to run an interactive shell.

However, the exact same code leaves the shell hanging indefinitely and no plot window is created.

the interactive mode switch plt.ion() call – again – works flawlessly from a vanilla windows shell but leaves the shell hanging when invoked from within the Emacs sub-shell.