Sam: Sure, Teshuvas HaRashba 3:214 quoted in the Beis Yosef end of YD 134. ?? ?????? ??? ???? ?? ?????? ?? ?? ????? ?? ??”? ??? ?? ????? ????? ?? ???? ????? ??? ??????? ???? ????? ?????? ??????. It’s not Avida l’Ta’ama, and I didn’t use that term. He is referring to an ingredient added intentionally, regardless of the lack of any discernible taste. Nevertheless, he apparently compares it to Ma’amid because both of them serve a purpose significant to the individual, despite their lack of taste.
Regarding your second point, the Tzemach Tzedek compared milk in dough to milk in chicken. Since there would be no Ma’amid on the milk with chicken, it follows that neither should there be a problem of milk with dough. Apparently, it is not accurate that “We are concerned with something becoming Assur because it has an Issur D’rabannan of having milk in it”. Rather we are only concerned for having perceptible milk in it.