Originally Posted by Loraura
Did you fill the black tank at least 3/4 full before dumping? Can do it by standing on the flusher to fill with fresh water.
I did. In fact, the tank was nearly full. From where the toilet sets to where it enters the holding tank is not a straight shot, as a result it takes very little waste to remain directly under the toilet and any liquid to drain into the tank.
Based on other threads, seems to be a common problem. Looks like the key is water. Plenty of water.