Hello, just to add a bit of information to this topic, we detected the same problem in a slightly different situation for a previous version of jBPM (in fact Drools Flow 5.1).
The situation also leads to a confussion of sessions and processes, and is described here:
http://comments.gmane.org/gmane.comp.java.drools.user/26332
We make use of state nodes in our processes, and have a part of process information that is stored in drools-facts. So, we need that our processes live in the corresponding session. Additionally, we make extensive use of timers, which forces us to have a blocking mechanism (which we have implemented based on the identifier of the session).
So, we need that processes live inside stateful sessions. We opened a JIRA issue related to this problem:
https://issues.jboss.org/browse/JBRULES-3108
In the meantime, we have patched drools flow 5.1 in order to have processes attached to stateful sessions (as explained in previous links).
greetings,
Jordi Alvarez