This happened to my group a few weeks back and I figured out how to reproduce it a few days ago.
This bug makes the game invite extra people into your warzone (you can't choose who the extra people are), one extra person will join the warzone for each person in your group excluding yourself.
The steps to produce this bug are:
- Be in a group with multiple people
- Group queue for a warzone
- Allow everybody else in your group to enter the warzone.
- When everybody has loaded click on the door to your ship
- For some reason when you start to load into your ship the other people in your group will get the popup to enter the warzone again. If they click Accept they will reload into the same warzone.
That is it, the game will now add another person into the warzone for each of your group members who hit accept. Your group members will still be in the warzone as well but they will no longer be part of the ops group. As far as I can tell they still get full benefits for being in the warzone.
This first happened to me when we had 3 people in a group, and the warzone had 2 extra people in it, but I have been testing and reproducing this with only 1 other person in the group. I am not sure if it works with a group of 4 but I would assume it would.
This works on both enetering or exiting your ship, I am guessing that it will work for any area where you get the load screen but the ship is the easiest one I know of.
We had a problem on The Voidstar where my group member hit Accept while he was still on the speeder, this caused him to spawn in the very last room and he had to wait until the enemy had broken through before he could join the battle. Not a huge problem but waiting until you are off the speeder might fix this.
All other warzones are fine as far as I know.