Playing the beta, I had the interesting circumstance that:
- I selected Public PvP lobby.
- The game searched for, and found, 4 team mates.
- It stalled on finding an opposing team.
- The 5 people on my team were moved to the Map Voting lobby, where we were given the choice of “The Algorithm” or “The Void’s Edge”, or no preference.
- During this process, it still said “Versus Maps: Setting up game” in the top right-hand corner.
- It sent us to play PvE in The Algorithm.
The only thing I could think of that might have caused this is that I hit Public PvE, then backed out before confirming Public PvE again. Perhaps this confused the system. I didn’t click to start matchmaking.
The Match ID was 20160411-a2041cec-f703-4b1b-8b26-aff693ffde70
Supporting images below:
http://imgur.com/vdLDHDQ
http://imgur.com/SxXE3Jw
Note in the first image where it says “Versus Maps” with a nice green checkmark on “The Algorithm”. 
The system also considered it a PvE game in the end, as it listed Mode as “Raid - Five Players”.