If you are alone and set "Players in party to 1" there is a high chance that people wont join. Try this if you are alone:
1. Set "Players in Party" to 1
2. Activate Very High XP + Force Host.
3. Search for a game type. Game should launch
4. Once Connected to Match, change "Players in Party" to 8
People should start joining but you may also get a "Forfeit Game" due to nobody joins in.
If you have fallowed my steps and that you are 2 or more in the party, be patient people will join soon or later. I had to reduce Lobby/Player search time to prevent Merging.