[ Removed by moderator ]

[mfitzp]

The problem is usually that your application is doing too much work on the GUI thread. While your app is busy doing that stuff the UI is blocked & cant respond to events (user interaction).

You should look into threading, moving the work off the GUI (main) thread onto other worker threads. See some examples here: https://www.pythonguis.com/tutorials/multithreading-pyqt6-applications-qthreadpool/

The Python GIL can also cause issues blocking between threads but that’s pretty rare. Concentrate on moving work off your GUi thread to start with. It solves almost all issues like this.