This is a bug in UD that I haven't fixed yet.
UD was first implemented many years ago before I took it over. It was originally done as a way to install a USB device and do a quick copy from/to the device. Unfortunately, the way it was implemented and has been changed over the years, it has broken the ability to click on the table header. I have it as a bug fix in UD tasks, but I suspect it will take some rewrite to make it work. It's not a high priority right now.
Clicking on the table header is one way to enable the help, but there are others. Press the F1 key, or click the help icon in the upper right of the page to toggle the help. In the non-tabbed view this is really messy because the help is enabled on all pages and you'll have to scroll through all the help to get to UD.