Further to latest software/firmware update on smartphone you may have noticed that display notifications are no longer popping-up on screen to alert you. Investigating for yourself, you may have also noticed the status bar unresponsive as you are unable to scroll down no matter how hard you try. Please refer to this article for the explanation and troubleshooting tips.
Phone's status bar gets disabled for pop-up notification after booting. For unknown reasons, caused by latest software update, for most app configurations, pop-up notification is set not to display on screen.
Check the option "Draw over other apps" configuration of the "LG System Server" whether it is set to "No".
("LG System Server" option appears in the list after "Show system" is selected.)
Settings → General → Apps
Menu Icon → "Configure apps" → "Draw over other apps"
Menu Icon → "Show system" → Check "LG System Server" whether set to "No" instead of "Yes".
After double-tapping "LG System Server", change the "Permit drawing over other apps" option from OFF to ON.
Then a popup titled "Unresponsive phone" will be displayed. Click OK and the status bar will become functionally enabled.