About the Friend invitation problem.
This is the Happy Wars Management Team.
From the Xbox One’s Happy Wars Contents Update 8 on December 1st 2015, there was the following issue:
Details
While inviting friends through Xbox One’s Friend/Party Applications to play the multiplayer section, the player & the invited friend cannot be allocated into the same team.
Temporary Solution
Currently this problem only happens if the friend is invited through the Xbox One’s Application. To avoid this malfunction from happening, please use the friend invitation in the Happy Wars multiplayer lobby menu instead.
We are aware of this issue and we are working to solve this problem as soon as possible.
Thank you for your understating.
About the Friend invitation problem