Mastery Myers and Merciless killer

Mystogreg

Playing On PC (Steam)

I finish a game with Myers doing 4 kills and got Merciless killer happy to finish the mastery Myers but mission didn't pop up and I got +2 pipe but that show me the picture so I don't understand (Got 5000points mini and 8000 max so no silver possible)

I got it once and don't know if it will reproduce.