Plasma: alt+key not working

After upgrading Kubuntu to 19.04, my alt key isn’t working in combination with other keys (like alt+tab). I need to enter settings -> input devices -> keyboard and change any option, after pressing “apply”, the keyboard works fine again. I have to do this every time I reboot my notebook. With xev and showkey I can see that the keypress is being recognized, but I don’t know what else can I see to find what’s the problem