A Matter Of Mesorah

The Gemara relates that there was a question that plagued Rabbah and Rav Yosef for 22 years. Rashi notes that the number 22 was not coincidental. Rabbah served as rosh yeshiva for 22 years before he passed away. During his entire tenure, this particular thorny question remained unanswered. Upon Rabbah’s petirah, Rav Yosef, who was blind, was appointed rosh yeshiva. Perhaps people viewed him as less of a talmid chacham compared to Rabbah. Rashi explains that Hashem wanted Rav Yosef to develop a reputation as an accomplished scholar as well. Therefore, Hashem granted him insight to solve the previously unresolved question.
Tosfos appear to be bothered by the fact that the query perturbed them for 22 years. It is clear from the Gemara that the question is based on a Mishnah that seemingly contradicts a postulate. Since the Mishnah is an authoritative source, it must be followed. Rabbah and Rav Yosef were troubled that the postulate in question could not be reconciled with a Mishnah. Tosfos wonder why these two great sages didn’t just dismiss the postulate as being incorrect. Perhaps they should spend a year or two trying to salvage the postulate; however, after some years they should have just dismissed the postulate as being incorrect, since it was clearly contradicted by a Mishnah. Why leave the question unresolved for so long?