As some of you may know, i've been working with Lady Gaga over the past year.
I produced some songs on her new album "ARTPOP" which is out today : Check out "Gypsy" and "Mary Jane Holland" !
Wasn't he only co-producer on "Venus", though? And it's clear that Gaga pretty much wants to claim sole responsibility for that track (she's mentioned that it's the first track she's produced by herself multiple times), so it was smart of him not to mention it.