Qt Quick Designer anchor buttons produce unexpected results

To reproduce the behavior in Qt Quick Designer (visual editor):

1. Create a rectangle and anchor it to the top left of its parent.
2. Copy-paste the rectangle.
3. In Layout, deleselect the top anchor and select the bottom anchor, insted.

-> The image height is reduced to zero (the property disappears from the code), and the rectangle does not move to the bottom of the screen.

In the visual editor, the height property is read-only and cannot be modified.

Even if, after two, you move the rectangle manually to the bottom of the page, the height property dispears.

This also happens even if you remove the old anchor settings first, by clicking the anchor buttons.

Similar things happen if you change the other anchors.