submersible exterminate bug

[(PSN)achmed9955]

I'm on the ps4 and in endgame territory so I've been farming kuria or tile farming with the help of a vid and it recommends a exterminate for this kuria. 

 this is the vid 5-2 is the kuria and  pain to find when the mission only gives you 10-15 tiles to work with and you can never end the mission because enemies alwayse stop spawning you kill all of them none spawn in the watter and the mission prefers ending in the watter with the same tile sets someone help please