Mordekaiser Bug when inside his ult at 3v3 maps he does not get vilemaw buff.

i do not get ghosted buff when inside my ult when my team killed vilemaw during my ultimate duration. is this intended or a bug ? what i meant as inside my ult as in fighting other champions using my ult and during that time my team took vilemaw and i didn't get buff . but my team did. QA? did i diei? nope. did i kill the target ? yes did your team get the buff ? yes did you win ? yes does it affect your gameplay ? not at all just takes whats rightfully mine. did your team kill vilemaw or was it enemies? my team killed it. in depth explantion how it occured . started a team fight at vilemaw and trapped on of the enemies in my ult killed him and my team killed vilemaw and carried on helping my team killing the rest. the next thing is i don't have the buff from vilemaw . but my team does.