There is what appears to me to be a UI bug in the Style Manager's Background control when working with the Body vs the other components. This issue is visible in @kuhelbeher screenshot from #2834 , but I will provide some simple steps to reproduce as well. Perhaps this issue is related to that problem.
Delete all the existing components until we just have the Body/wrapper
Select Body and set a background image (notice what the Background UI looks like at this point for the body image setting)
Open the blocks and drag a Navbar to the top of the page
Set a background image on the Navbar as well and it should render in the editor
Select the Body/wrapper again at this point and now look at the Background UI (it appears that it knows that a non-default setting has been made since the label has changed color and the reset icon is visible, but Layer 1 is NOT shown)
Select the Navbar in the editor and compare what it displays in the Background UI (Layer 1 is correctly shown)
There is what appears to me to be a UI bug in the Style Manager's Background control when working with the Body vs the other components. This issue is visible in @kuhelbeher screenshot from #2834 , but I will provide some simple steps to reproduce as well. Perhaps this issue is related to that problem.
Navbar selected
Body selected
Version: 0.17.19
Are you able to reproduce the bug from the demo?