I just did all 3 areas overthrow bosses in a row just for the impasse secret keeper to not spawn. So I did it all again and guess what, it didn't spawn. So can someone either tell me what i'm doing wrong or can other people let me know if they've had this bug too? This is exactly what I was afraid of happening after hearing you have to do 9 entire waves of overthrow back to back. Time being wasted was inevitable.