Need help!

[FlawlessHappiness]

(string &in asTimer) This means it's a timer..

When you make a collide function like AddEntityCollideFunction, it will not work with a timer function.
I would do it like this:

Spoiler below!

void OnStart()
{
AddEntityCollideCallback("Player", "monact", "startmonster", false, -1);
AddEntityCollideCallback("Enemy_Grunt", "PNScriptArea", "startmonster", false, 1);
}



void startmonster(string &in asParent, string &in asChild, int alState)
{
SetEntityActive("Enemy_Grunt", true);

for (int i = 1; i <40; i++)AddEnemyPatrolNode("Enemy_Grunt", "PathNodeArea_"+i, 0, "");
}

Are you sure you want this:
AddEntityCollideCallback("Player", "monact", "startmonster", false, -1);

To be false? This means that if the player leaves the area "monact" the monster will go active again.. Maybe you should set it to true?