Our 2010 had a hepvo valve (google it) on that drain instead of a P trap. It's usually located in the basement and can be removed by loosening the end connections. Do not run something down the drain or use anything but a soft brush to clean it or you will damage the membrane inside and have to buy a new one. We use a drain screen in the shower to catch the hair and keep the valve clean without having to do anything with it.
Dick, Joyce, Diego, Picatso and Gustav
2017 3720 RL, and 2013 HC 343RL
2017 3500 Dodge Maxi DRW 4X4, Pullrite Hitch, IS, Disk Brakes, 3rd AC, Winegard Traveler, Bathroom door mod, Dometic 320, couch for desk swap, etc.