It is either of these…
Bad Oil = Replace the oil ===> Hyosungs love Motul 7100 and Silkolene Pro 4 oils. Very very good oils.
Clutch Plates too worn or problem with thrust bearing inside clutch ==> Overhaul clutch
ARM behind engine for clutch cable needs to be closer to sprocket cover when bike is in neutral (Clutch Adjustment Tutorial)
FOOT SHIFTER assembly is dry and needs grease , ==> Lubricate the joints around the foot-shifter assembly.
Rear Wheel Chain is too slack or too tight ==> Check chain tension (yes believe it or not) , it can affect neutrals too.
// Meditation doesn't mean you have to sit still....