Here it is: Bug in Teams mode
And a related bug that needs fixing: Invite Bug
Bug: The same player in 2 teams

More info: I invited alyeasin93. At the same time as Cacka3 invited alyeasin93. Before the game started I got a message "your teammate left the matchmaking", but the game started anyway.
alyeasin93 was in both teams, but could move only blue pieces.
Both alyeasin93 and I lost rating points.
I think it is enough info for the developers to fix this issue.
I know, that it happened already, but could not find that forum topic, so create a new one.
alyeasin93 in 2 teams:
In the next game you can see that alyeasin93 lost 33 rating points (and I lost 27):