I have enabled Full Screen Mode as well as Always Hide Toolbar, but both the System Bar and Toolbar return on swipe.
To stop the top toolbar from displaying on swipe down please turn off "show toolbar on swipe down". Please note after doing this you must use the multi-tap method to access settings/exit.
The bottom navigation bar will always show on swipe up as this the way immersive mode works on Android. After a few seconds it will hide itself again.
More information on toolbars can be found here: https://kioskbrowser.userecho.com/topics/2306-full-screen-mode-hiding-the-toolbar/
Customer support service by UserEcho