Setting teams to team index will solve this problem. But it’s not ideal.
Players are added to one team in join in progress and not to other teams according to island settings. I don’t know if this bug or another join in progress bug is causing it.
win on time out is probably enabled for multiple teams, usual culprit. check for this setting and untick it in team setting devices in 1.0 (not sure about uefn but it will have the setting somewhere) , it’s used for things like hide and seek games as to let hiders win if they alive when time ends. If both teams win on time out when time is up they both win, resulting in a draw, untick for all teams.