Apparently note 5 has know errors on wireless charging. As soon as flip closes and Screensaver turn on disabling screen, it will stop charging except you find a way to keep screen active. Some forums recommend use Daydreams Screensaver and set this enables only when it is charging.
I had same issue, tested work around and works, however I moved to use cable because I think life cycle of screen will kill if I continue charging always with screen on., but pass you the tip in case works for you.
For fast charging I experienced issues too. I had factory charger and cable apparently try die but telephone apparently continue charging but takes long hours to raise, the again found some forums that explain the version of charger and cable OEM are cheapest to reduce price of sale and purchasing the original accessory the quality would be quite different (better). Well I followed the tip and again worked for me.