Constraint matches dialog throws IllegalStateException in Machine reassignment example with data set model_a1_1

Exception in thread "AWT-EventQueue-0" java.lang.IllegalStateException: The constraintMatchTotal (org.optaplanner.examples.machinereassignment.solver/serviceConflict=0hard/0soft) could not add constraintMatch (org.optaplanner.examples.machinereassignment.solver/serviceConflict/[MrService-1]=0hard/0soft) to its constraintMatchSet ([org.optaplanner.examples.machinereassignment.solver/serviceConflict/[MrService-53]=0hard/0soft, org.optaplanner.examples.machinereassignment.solver/serviceConflict/[MrService-35]=0hard/0soft, org.optaplanner.examples.machinereassignment.solver/serviceConflict/[MrService-5]=0hard/0soft, org.optaplanner.examples.machinereassignment.solver/serviceConflict/[MrService-36]=0hard/0soft, org.optaplanner.examples.machinereassignment.solver/serviceConflict/[MrService-31]=0hard/0soft, org.optaplanner.examples.machinereassignment.solver/serviceConflict/[MrService-1]=0hard/0soft, org.optaplanner.examples.machinereassignment.solver/serviceConflict/[MrService-16]=0hard/0soft, org.optaplanner.examples.machinereassignment.solver/serviceConflict/[MrService-78]=0hard/0soft, org.optaplanner.examples.machinereassignment.solver/serviceConflict/[MrService-50]=0hard/0soft, org.optaplanner.examples.machinereassignment.solver/serviceConflict/[MrService-9]=0hard/0soft, org.optaplanner.examples.machinereassignment.solver/serviceConflict/[MrService-2]=0hard/0soft, org.optaplanner.examples.machinereassignment.solver/serviceConflict/[MrService-6]=0hard/0soft, org.optaplanner.examples.machinereassignment.solver/serviceConflict/[MrService-26]=0hard/0soft, org.optaplanner.examples.machinereassignment.solver/serviceConflict/[MrService-7]=0hard/0soft, org.optaplanner.examples.machinereassignment.solver/serviceConflict/[MrService-4]=0hard/0soft, org.optaplanner.examples.machinereassignment.solver/serviceConflict/[MrService-3]=0hard/0soft, org.optaplanner.examples.machinereassignment.solver/serviceConflict/[MrService-0]=0hard/0soft, org.optaplanner.examples.machinereassignment.solver/serviceConflict/[MrService-47]=0hard/0soft, org.optaplanner.examples.machinereassignment.solver/serviceConflict/[MrService-66]=0hard/0soft]).
	at org.optaplanner.core.api.score.constraint.ConstraintMatchTotal.addConstraintMatch(ConstraintMatchTotal.java:96)
	at org.optaplanner.examples.machinereassignment.solver.score.MachineReassignmentIncrementalScoreCalculator.getConstraintMatchTotals(MachineReassignmentIncrementalScoreCalculator.java:519)
	at org.optaplanner.core.impl.score.director.incremental.IncrementalScoreDirector.getConstraintMatchTotals(IncrementalScoreDirector.java:95)
	at org.optaplanner.examples.common.business.SolutionBusiness.getConstraintMatchTotalList(SolutionBusiness.java:247)
	at org.optaplanner.examples.common.swingui.ConstraintMatchesDialog.resetContentPanel(ConstraintMatchesDialog.java:76)
	at org.optaplanner.examples.common.swingui.SolverAndPersistenceFrame$ShowConstraintMatchesDialogAction.actionPerformed(SolverAndPersistenceFrame.java:625)
	at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
	at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
	at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
	at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
	at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
	at java.awt.Component.processMouseEvent(Component.java:6533)
	at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
	...