Flipable draws incorrectly when rotated and the angle is 45°

There is no problem when rotating Flipable to 30° angle, but when I change the rotation angle to 45°, the content that Flipable draws becomes the item on the back.

I provided a simple qml code, the front Rectangle item color is "red", the back Rectangle item color is "yellow".
using command: "qmlscne --no-scaling test.qml", waiting for the application to quit, you will get two images "test_qml_30.png" and "test_qml_45.png" in current folder.