Just to add: while it may not have said "Slow Charging" prior to your issue happening, it always has been slow charging. The stock wall charger is 1.8A and the USB port on a PC is 500mA (0.5A).
OK, let's see we can fix your issue. If you click the Settings icon, scroll down to PC Connection (in the System section) and tap that, you should see "Select USB connection method" and "Ask upon connecting". To be asked each time like you used to be, put a checkmark next to it. If you want to just change the default, tap the Select USB connection method and see what it's currently set to. You should be able to change your settings there (Charge phone, Media sync (MTP), Tethering, LG Software and send images (PTP).
Good luck.