After applying the 2020.0.7 update, the top navbar changed to a white background (previously it was green).
On the PHPM Theme tab, the Navbar class setting shows "navbar-dark-success", and the preview panel below shows the top navbar in a grey hue (so the theme appears to have changed in this update).
However, if I regenerate the project then the top navbar still shows in white (even if clearing browser cache).
Also, if I click the value to change it, no dropdown list is displayed (unlike with the Sidebar class option above), and I have to manually click the dropdown arrow in order to see the list of options.
If I select one of those options then the preview pane reflects the choice and regenerating the project applies the selected colour choice to the top navbar, but the theme name is no longer displayed as the theme settings have changed.