Well, now this solution may be a little long but I’m sure it works! (If you had it hard to apply tell me so I find something else).
I assume you use class selector to change team. Now what you do is you forget everything about coding and just work with devices.
I’ll assume that the zone that changes players teams is square shaped.
I’ll assume the team that players get switched to is Team Index 3.
I need you to make the zone gets disabled after someone enters it and get team switched.
Plus find the option that it changes the team of the triggering player only.
1- Go add Trigger Device, and change the value of how many times it can be triggered before getting disabled to 1 (find this option in it).
2- Also in the Trigger Device first disable all check boxes that talk about triggering because we don’t want it to work if someone gets close to it, we’ll do it manually.
3- Scroll down to Trigger Device functions → Trigger → When Mutator Zone → Player Enters it
Now even if someone else enters the zone it won’t change his team because Trigger Device is able to get triggered once only as you set it above.
4- Go to ‘Class Selector’ that is responsible for changing team, scroll down to its functions and make ‘Change player to team’ → when Trigger Device → Gets Triggered
Also now the player team was changed to 3 right?
Last step is add Mutator Zones out of the current mutator zone (surrounding it) then go to trigger scroll down to its functions Reset or Active one I forgot it → let it reset when Team Player 3 enters the new surrounding zones (which in fact means he got out of the main zone)
So the trigger device now works again and can change team of anyone new who enters the Zone.
Honestly I’m away from PC so the answer may gets you lost abit because words aren’t accurate but if you are getting most of what I am saying tell me so I take the answer to the professional level.