alignmentBaseline callback issue

[immanuelf9]

The alignmentBaseline property does not work when supplied a callback, but does work when supplied a text string. In the screenshot below the following do not produce the expected output:
alignmentBaseline: edge => {return 'top'}
alignmentBaseline: edge => { return (edge._data.isReverse ? 'top' : 'bottom') }

However this does
alignmentBaseline: 'top'