Fortunately, there appears to be a 100% reliable work-around. The problem seems to happen when you wipe in one instance of Denova (e.g. Denova 1) and get put into a different instance (e.g. Denova 2) when you re-enter. The workaround is to leave one person (dead or alive) inside the instance until someone releases and re-enters. That ensures that you stay in the same instance you were in (with dead trash).
this issue also exists in KP