I don't know when this started but I noticed that I was not getting pop up alerts after programs were updated. I checked in settings and alert-mode was switched off. I didn't do this and it was working quite recently.
If I click on it the radio button change for a moment and then back to off. I never see the blue colour of the on position.
I can just re-install but having settings change by themselves is not good. Nobody else has access to my laptop.