ConcurrentModificationException in DB Query handling

This happens frequently with Simupedia use.

Exception in thread "QueryListening" java.util.ConcurrentModificationException
    at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:909)
    at java.util.ArrayList$Itr.next(ArrayList.java:859)
    at org.simantics.db.impl.query.QueryListening$Scheduler$1.run(QueryListening.java:128)

After the exception, the DB stops responding any requests. The only way to proceed is to kill the application.