Oh interesting & unfortunate. I can confirm I use one display, running it on my TV. I must say, big picture on my desktop session gets closer to the experience than when I initially set this up. I hope they add the quick settings overlay to the normal big picture mode some time. I might switch back to running on my desktop session.
I definitely did not run into this many issues when I installed it… Just kinda worked for me, so I’m not sure where you should investigate