I finally made it to work on xbox one too, made as mentioned on this post: UEFN Live Sessions Don't Launch Onto Xbox One - #17 by Flak
I uninstalled, restarted the xbox and reinstalled the game. Then open the game, launched the uefn project, and finally (after a few tries) it opened my project 
It works, but it’s so frustrating that to launch the project on my pc or Xbox I have to try like 3 times for it to finally work 
but apparently, case solved!
It just needs some improvements on matchmaking, I hope the devs keep an eye on it