not fully understanding what you mean by 'not working sometimes'
are you saying it doesn't show the notification icon for some of the apps?
it is possible some of the settings were changed while updating, especially if the update is a major update like OS update then it can happen. Not sure what sort of update you had but check your settings again.
If you feel that it's as it should be, then when it happens again... report immediately to samsung members app > get help > error report
What is the device model number and software version (settings > about phone > software information > build number (last 4 digits)) ?