The ocean monument don't spawn guardians

I found a guardian monument and i clean the water and make a farm but i go to my base and i kill a pillager and start a raid the problem is they are invicibles and me and my friend change the difficult to pacifist and go back to hard i close the game and open again and the raid in not hapening and i back to the monument and put water and finish the farm and dont spawn any guardian i dont know whats happening but i do this one time before this and the guardians continued spawning.