TextArea in GridPane will not stretch vertically

Using a GridPane to implement a simple form, I have a column of labels and a column of controls. The bottom right control is a text area. The bottom row and right column are set to grow always. The TextArea max width and height are set to MAX_VALUE. But the TextArea will only grow horizontally, and adjust a little bit vertically - but it will stop crowing vertically such that it does not fill the "cell" in the GridPane.
(Sample code on the way.)

Same issue also appears in HBox.