PyQtGraph plotting problems due to PySide6 update

Summary

Updating my PySide6 installation to PySide6-6.9.1 caused my installation of PyQtGraph to stop plotting correctly. Reverting to PySide6-6.9.0 fixed this issue.

The Problem

I created a new virtual environment for Python development and installed the necessary libraries for development using PyQtGraph. Naturally, I installed the latest versions of the libraries that were available. This included PyQtGraph and PySide6. When I ran some known good code, the plot canvas showed but no data was plotted. I checked using example code from the PyQtGraph GitHub and got the same behaviour for several of the examples. Axis and canvas were displayed, but no lines.

The solution

I tried running the Python code using an older virtual environment and it worked! I checked the versions of Pyside in the site-packages folders for the two virtual environments. The older virtual environment used PySide6-6.9.0 and the new virtual environment used PySide-6.9.1. I replaced PySide6-6.9.1 in the new virtual environment with PySide6-6.9.0. This worked to fix the plotting problems.

Background

I use PyQtGraph to display accelerometer data from a programmable smart watch. This is used to develop algorithms that recognise intentional movements made by somebody who is disabled. I incorporated these algorithms into code that enables the user to access communication software to create speech or adjust environmental controls. More details on this project are here.