Do the ECF's teach Sola?

If the ECF's really believe in Sola Scriptura, as some Protestants claim, we would expect them to believe the same things that Protestants believe, correct? Because Protestants deny the doctrines of Mary and the Eucharist. But what do the ECF's believe?

Let's take this example because it was recently brought up on the Internet:

If Cyril of Alexandria believed in Sola Scriptura, why didn't he deny the doctrine of Mary, the Mother of God? or the Eucharist as body and blood of the Lord?

But I am also quite interested in why Protestants dare to claim that the ECF's were anything but Catholic. Please. Let's discuss all their teachings and their beliefs. It isn't that hard. They were steeped in Catholicism.  All of them.  There is not even one which was not.

So, show me, if St. Cyril believes in Sola Scriptura, why does he also teach that Mary is the Mother of God, and a Perpetual Virgin?

Cyril of AlexandriaI have been amazed that some are utterly in doubt as to whether or not the holy Virgin is able to be called the Mother of God. For if our Lord Jesus Christ is God, how should the holy Virgin who bore him not be the Mother of God? (Letter to the Monks of Egypt1 [A.D. 427]).

And why does he teach that we should keep the Traditions?
"[H]old fast the faith in simplicity of mind; establishing the tradition of the church as a foundation, in the inmost recesses of thy heart, hold the doctrines which are well-pleasing unto God." Cyril of Alexandria, Festal Letters, Homily 8 (A.D. 442).

And we can go down the line with every single Early Church Father.  They were all priests or Bishops who confected the Eucharist, celebrated the Mass, believed in the Authority of the Church, commanded authority over their flocks and on and on.

Sincerely,

De Maria