After installing kmix my Meta key and screen edges feature stopped launching the app launcher. The issue was in the ~.config/plasma-org.kde.plasma.desktop-appletsrc file. Where the [Shortcuts] global entry had been changed to Meta+Alt+F1. I changed it back to Meta and saved the file. It's now fixed and working fine. Just thought others may need to know and I couldn't find a similar thread in the forum.

Thanks, it has been useful to me, I had it in Alt + F1, I have already changed it to Meta 🙂