I find myself getting about 90% success rate by power cycling the Wii U between games and deleting cookies prior to doing the exploit. So if I am playing Star Fox Zero and want to play Mario Kart 8, I quit Star Fox, turn off the console, turn it back on, load up the Web Browser, delete cookies, go to the URL on my self-hosted server, click on 5.1.1 options, click on Web Browser once again after getting kicked back to the menu, then go to Loadiine to select Mario Kart 8. It may not be required, but it works for me. I only have about 5 Wii U games on Loadiine but that's really all I can think of that I want