Issue rendering JTable with AbstractTableModel

Question

I've been trying to display a JTable and have been getting strange artifacts.

I have a class that extends AbstractTableModel. I'm not sure why I'm getting these artifacts. How do I get JTable to display correctly?

Below is my TableModel

public class AllScansModel extends AbstractTableModel {

private List<WasScan> wasScans;
private String[] columns = new String[] { "Name", "Type", "Profile", "Date", "Status" };

public AllScansModel(List<WasScan> wasScans) {
    this.wasScans = wasScans;
}

@Override
public int getRowCount() {
    return wasScans.size();
}

@Override
public int getColumnCount() {
    return columns.length;
}

public void setValueAt(int rowIndex, WasScan wasScan) {
    wasScans.set(rowIndex, wasScan);
    fireTableRowsUpdated(rowIndex, rowIndex);
}

public void addValue(WasScan wasScan){
    wasScans.add(wasScan);
}

@Override
public Object getValueAt(int rowIndex, int columnIndex) {
    WasScan scan = wasScans.get(rowIndex);
    switch (columnIndex) {
    case 0:
        return scan.getName().getValue();
    case 1:
        return scan.getType().toString();
    case 2:
        return scan.getProfile().getName().toString();
    case 3:
        return scan.getEndScanDate().toString();
    case 4:
        return scan.getStatus().toString();
    }
    return null;
}

@Override
public String getColumnName(int column) {
    return columns[column];
}

public void updateTable(List<WasScan> wasScans) {
    this.wasScans = wasScans;
    fireTableDataChanged();
}
}