Rob
Ansys Employee

The first problem is a missing setting somewhere in the model. If you've been turning things on and off you may have caused a glitch in the set up. In that case you may have to start again if you can't find it. 

The incomplete message means you're not tracking particles long enough: they're running out of integration steps before leaving the domain. However, the continuity equation is very definitely not happy so I suspect incomplete particles are the least of your problems. 

Why are you using DDPM over DPM or Eulerian multiphase model? DDPM isn't used that commonly so I wonder if you need it.