Odd behaviour since upgrade to 2024.3

Afternoon Everyone!

This is really odd. The go to definition (ctrl-b) has stopped working, the refactoring tools don't execute anymore. So right click on a new property and choose “Create Property ‘xxx’” does nothing except display a tooltip saying action cancelled!

I have uninstalled and re-installed rider, web storm and data grip in the hope that whatever crazyness would go away but no joy. 

Any ideas?