Black Tank continually registering full

[Irishman2014]

Hello all. We have a 2014 Cougar CCH 27RLS that we purchased from a dealer about 2 months ago. We've used it a couple of weekends and for the most part its fantastic and we really enjoy it (first timers). There's a control panel that is for turning on the lights, HW tank, water pump, slide out, etc. That same control panel also tells us how full our water tank, gray tanks and black tank are. I've dumped our tanks (black first followed by the two gray tanks). I know that they are emptying because you can feel the water rushing out through the dump hose. I then rinse out the black tank by utilizing the built in spray system (keystone calls it "no fuss flush kit"). When I check the status of the tanks on the control panel it shows the gray and water tanks are empty, but the black tank is 3/4 to completely full. Anyone run into this before? If so, how did you correct it? Thanks in advance for your help.