i think this issue have annoyed most of us by now!
I hope blizzard technicans will solve this problem, it is very bad..
Fortunaly i have notice a workaround for this:
Join a public bountie game
it will be only you and one more, ask that person if you may invite him/her to a /4 game
leave that game, join a new
=you and a new one
invite the first one
he comes into the game
and the automatic starts almost directly for an /4 person to enter
i rly cant understand why, this will be hard for them to solve!?
Have a nice day!