Change playback speed Wavelab Pro 10

i am doing quality control on a set of audio books. All of the content is signed off on and I am just going through checking that there are not any line repeats or obvious editing issues. I would like to listen back at x1.5 the playback in order to speed the process up. I have gone into the playback speed menu that is available near the transport at the bottom of the window. I set it to 150%, select the “clock” icon so that it is highlighted and as far as I can tell from the online documentation that is all I need to do. However, when I hit play, the playback speed is not changed at all. Is there another step that I am missing?

Please use WaveLab 10.0.40


Thank you so much.