I checked out the clean Zero project to verify as well: As soon as the aside menu is collapsed by default and the Accordion submenu toggle is active, the Administration(or any other) submenu doesn't open. The menu stays in state 'Hover/Active' but nothing happens. As a consequence if you change the page to dashboard(doesn't have a submenu) f.e. you can never enter Administration again. So there is no possibility to change the setting and you have to clear the database entry. For the submenu toggle 'Dropdown' the menu opens.
I guess this is a bug or did I oversee some option?
Regards.