I've got the same problem.
I Followed Kris' article but when double-clicking on the single process instance in the "Process Instances" view, I get an error in a pop-up "Could not find process with id com.sample.evaluation".
But when I expand the RuleFlowProcessInstance object in the "Process Instances" view, I do see the property processId="com.sample.evaluation" so I'm a bit confused.
Any suggestions?
Thanks
Maïté