Ok here is a wild idea that may work. On my Cedar Creek the black tank flush was missing the rubber washer that is required to seal between the hose and the hose connection in the docking station. This prevents water leaks when the hose is installed. See if the washer is missing or cut simply replace/install one if required. See if this stops the water leak.
Just a guess as I can't see the your unit.
2016 34RL CC; 2008 Ram Mega Cab 2500HD, 6.7L, 68RFE 6 speed, 4X4, Smarty S67