Some layout algorithms replace label data when placing labels because not all label placement policies are suited for automatic label placement. In other words, depending on the layout algorithm and the layout settings you did use, this is the intended behavior.
That begs the question, which algorithm and what settings did you use?
P.S.: Please do not "hijack" old topics. While the original topic does relate to auto-rotation of labels, it does not relate to layout calculations in any way.
