mod.AISetUnspawnOnDead not working.

Maybe I'm doing something wrong, but for me the function AISetUnspawnOnDead() is not working at all. AI Soldiers are spawned via SpawnAIFromAISpawner() but despite setting unspawn on dead to false, as soon as they die, just leave the game. Is there any other settings which needs to set to prevent the AI from leaving the game? Thanks in advance.

The definition of the mentioned functions :

// Use this on a spawner to determine if AI soldiers spawned will leave the game after they are killed.
export function AISetUnspawnOnDead(spawner: Spawner, enableUnspawnOnDead: boolean): void;

 // Spawn one AI soldier from a specific AI Spawner.
export function SpawnAIFromAISpawner(spawner: Spawner, team: Team): void;