I have two Move controllers, both connected to the Playstation, both can also be used outside of the game. However as soon as I start Just Dance 2018 only one of them (the one I had turned on first when starting the Playstation) turns blue and can be used. The other one turns white, I cannot use it with a second dancer card, I cannot use it in game at all.
I think that by now I am also far enough into the game to have unlocked everything.