As for St. Thomas, YES, he was not always correct. He publicly taught that Mary was not immaculately conceived which is now an infallible dogma of the Church. He was clearly wrong with respect to this issue.
Catholic Encyclopedia: “St. Thomas at first pronounced in favour of the doctrine in his treatise on the “Sentences” (inI. Sent. c. 44, q. I ad 3), yet in his “Summa Theologica” he concluded against it. Much discussion has arisen as to whether St. Thomas did or did not deny that the Blessed Virgin was immaculate at the instant of her animation, and learned books have been written to vindicate him from having actually drawn the negative conclusion. For this controversy see: Cornoldi, “Sententia S. Thomae etc.”, (2nd ed., Naples, 1870); Ronard de Card, “L’ordre des Freres-precheurs et l’immaculee Conception” (Brussels, 1864), Pesch, “Prael. dogm.” III (Freiburg, 1895), 170; Heinrich-Gutberlet, “Dogmat. Theol.”, VII (Mainz, 1896), 436; Tobbe, “Die Stellung des hl. Thomas zu der unbefl. Empfangnis” (Munster, 1892); C. M. Schneider, “Die unbefl. Empfangnis und die Erbsunde” (Ratisbon, 1892); Pohle, “Lehrbuch d. Dogmatik”, II (Paderborn, 1903), 254. Yet it is hard to say that St. Thomas did not require an instant at least, after the animation of Mary, before her sanctification. His great difficulty appears to have arisen from the doubt as to how she could have been redeemed if she had not sinned. This difficulty he raised in no fewer than ten passages in his writings (see, e.g., “Summa Theol.”, III, Q. xxvii, a. 2, ad Sum). But while St. Thomas thus held back from the essential point of the doctrine, he himself laid down the principles which, after they had been drawn together and worked out, enabled other minds to furnish the true solution of this difficulty from his own premises.”