I created a new palette "Lector's palette" and a new style "incipit". After creating them, I clicked out any palette on the pane. I got:

i.e. a duplication of an existing palette opened to show all its palettes. My new palette and style are nowhere to be seen. So I close the pane and reopening Highlights to get:

Now my new palette shows up and I can add more styles ...
I've already reported a variation on this theme.