TYPO3 Core

Given the following TCA configuration

        'select_34' => array(
            'exclude' => 1,
            'label' => 'SELECT: 34 maxitems=1, renderType=selectSingleBox',
            'config' => array(
                'type' => 'select',
                'renderType' => 'selectSingleBox',
                'items' => array(
                    array('foo 1', 1),
                    array('foo 2', 2),
                    array('foo 3', 3),
                    array('foo 4', 4),
                    array('foo 5', 5),
                    array('foo 6', 6),
                ),
                'maxitems' => 1,
            ),
        ),

The selectSingleBox shows INVALID VALUE "" for new records. This happens only with maxitems = 1