Well its brand new so you could always have some plastic scraps blocking it. When they drill the tank holes the scraps go into the tank. So you might have some 2 or 3 inches round scraps laying just right?
Did you used enough water to help flush tank? Many folks use toilet water sparingly and if you started with a dry tank more water might help to flush it out. I always add about 2 or 3 gallons of water to my freshly empty black tank then lots of water between flushs (as long as your not worried about running out of water on your trip).
Your model should have a black tank flush as well. Hook it up and let it run for 5 minutes ... see if it will dump. Then try 10 min but dont overfill tank (you can check tank level gauge or look down the tolet with a flash light so see height of water).
Drive arond with full black tank and curvy rough road. Use lots of choppy brakes and see if that loosen it up?
Let us know how it goes.
Oh yeah.... congrats on your new RV. Hang in there ... you will get all (well most) of the bugs worked out first year (But new ones will arise
2017 Axis / 25.4: Big Foot Levelers, Aims 1200 Watt inverter, Ceramic Window Tint, Full River AGM 6V batteries, Front Hellwig Sway bar / Rear Track Arm, Safe T Plus Steering Stabilizer, PD 4655 converter, Hard Wired Surge Guard, WEboost + WiFi Ranger, LED Headlights/Driving lights, TPMS, Surge tank, Tornado flush, Viair Compressor