@herf I'm sorry for the late reply, but yes, unfortunately this still happens. As for alt-tabbing, believe me, I have tried, thats why I was asking for the preferences file so I can manually add it, but it didn't work.
Like I said before, Fortnite is kind of buggy when alt-tabbing, etc. I have to open the Flux UI so I can alt tab back to Flux DIRECTLY, and even then Fortnite doesn't appear. I tried not opening the Flux UI, and alt tabbing from the game, but it doesn't take me to my desktop (hence buggy, and hence opening the Flux UI). After alt-tabbing, I press the windows key to gain access to my task bar, right click flux, disable, and once again Fortnite is missing BUT "Search and Cortana" shows.
Like I said, Fortnite is very buggy, but the same thing happens with League of Legends, it doesn't appear. Is it possibly because the apps are being launched in 32-bit mode or as admin?