I also play on JoiPlay and I have the very same glitch, do u also have almost the same thing the second time u go to the eighth floor in the Shine town? It might be a mobile only glitch.
Finally got time to grind a little more here. Got on 8th floor first time went excellent then on return I have same issue like you page is blank no returnbutton no nothing. Also it seems that shintie town (d...ug dealing thing) is broken aswell have quest to sell 10 sold more than 30 still can't finish it