Michael,
If Woodturner PRO is not running, you should see that it is not possible to click on either the toolbar button that shows the segmented bowl (when hovering over it, it says 'transfer to wtp') or File > Transfer to Woodturner PRO. As soon as you start WTP, both of those become clickable. If you click either, the WTP icon starts flashing which means you need to switch to that program. At that time, a dialog box should already be present that lets you specify either the height or the width and clicking OK transfers the wall profile.
If any of the preceding steps doesn't happen, it means that the two programs cannot find each other in your computer's memory and you need to reboot to fix this.This is something I see about once every year and, unfortunately, there isn't any way to know why the operating system has a corrupted memory table.
If rebooting doesn't fix this, it is likely there is a permissions issue that is preventing the two programs from completing this task. This is also something I should be able to resolve using screen sharing.
Sorry that this is frustrating, but if you are doing it correctly and it isn't working, there is a problem on your computer that I can likely fix and I am more than glad to do that.