Queries requesting for 2 columns against two joined selectors using QueryObjectModelFactory will fail at QueryResultColumns.java line 254 with a stack trace similar to:

java.lang.AssertionError
at org.modeshape.jcr.query.process.QueryResultColumns.<init>(QueryResultColumns.java:254)
at org.modeshape.jcr.query.process.QueryResultColumns.subSelect(QueryResultColumns.java:317)
at org.modeshape.jcr.query.process.ProjectComponent.<init>(ProjectComponent.java:38)
at org.modeshape.jcr.query.process.QueryProcessor.createComponent(QueryProcessor.java:284)
at org.modeshape.jcr.query.process.QueryProcessor.execute(QueryProcessor.java:88)
at org.modeshape.jcr.query.process.QueryEngine.execute(QueryEngine.java:140)
at org.modeshape.jcr.query.lucene.LuceneQueryEngine$1.getResults(LuceneQueryEngine.java:153)
at org.modeshape.jcr.query.JcrQuery.execute(JcrQuery.java:119)

I have checked in a possible fix by attempting one more time looking up the property name instead of the column name.