If i'm right, then you are running a script for the comp like "Expantion Zerg Campaign Difficult". this is causing the comp to burrow the lurker, so it can attack. since you need to load it in the beginning of the game, you can set a wait period for the script.
Conditions:
always
Actions:
wait 30000 millaseconds
execute ai script 'expantion zerg campaign easy/difficult/insane' at location X