A.T. Robertson Commentary John 12:37

"But though he had done so many signs before them, yet they believed not on him:" — John 12:37 (ASV)

Though he had done so many signs before them (τοσαυτα αυτου σημεια πεποιηκοτος εμπροσθεν αυτων). Genitive absolute with perfect active participle in concessive sense of ποιεω.

Yet they believed not on him (ουκ επιστευον εις αυτον). No "yet" in the Greek. Negative imperfect active of πιστευω, "they kept on not believing on him," stubborn refusal in face of the light (verse 35).