Not sure what the problem is, but believe it's related to how the HTML works with the pinned html already there. Ie:: I have played around with different html until it basically works. When I fist added my code it goes to the maintenance page correctly. See image. If I close browser and go back in the bottom tag line is gone.
So, the original problem appears to have fixed itself after I changed the html. But now the tag line to login for admin ((Follow this link to disable maintenance mode)) is gone.
Also I show you my User Settup, but I really dont want to enable html for users. (not sure) but if I disable it the code disappears.