No, the Immaculate Conception was not held as divinely revealed by the OUM. Otherwise, there need not even have been a solemn definition.
I told you one of the reasons for solemn definition - "One of the many reasons the pope solemnly defines a doctrine, is to erase all opposing opinions - for all time."
Go back and actually read
my post quoting Pope Pius IX from Ineffabilis Deus and you will find he explains it most beautifully, I quoted a part of it below for you. He literally says that the Catholic Church has ever held the Immaculate Conception as divinely revealed. Where he says "and as contained in the deposit of heavenly revelation", he is saying the doctrine has always been contained in the ordinary and universal magisterium - that's what he is saying.
Why are you saying it was not held as divinely revealed by the OUM? I assume by that, you mean it was never held as divinely revealed by the Church,
so what you are saying as if it is truth, is a word for word contradiction of the below infallible teaching."The Catholic Church, directed by the Holy Spirit of God, is the pillar and base of truth and has ever held as divinely revealed and as contained in the deposit of heavenly revelation this doctrine concerning the original innocence of the august Virgin — a doctrine which is so perfectly in harmony with her wonderful sanctity and preeminent dignity as Mother of God — and thus has never ceased to explain, to teach and to foster this doctrine age after age in many ways and by solemn acts.." - Ineffabilis Deus
What you cannot accept is what the Church, in this instance through Pope Pius IX, teaches, namely, whether or not the teaching is contained in the Ordinary and Universal Magisterium or the Extraordinary Magisterium, they are both infallible. There is no difference because the Church's Magisterium is only always infallible.
Contrary to the NO ideas you keep promoting as Church teachings and all theologians' teachings and the magisterium's teachings and dogma of faith teachings, dogmas are defined, not not made up, not by popes and not by the totality of bishops in union with the pope. Dogmas are truths or doctrines, that have always been contained in the Church's Magisterium, just exactly as pope Pius IX teaches.