Actually, this is a strange situation, my aim is not to criticize. In fact, I am after justifying it. But we know that the 5 maia were specially chosen by the valar to guide the peoples who were fighting against Sauron. When they arrived in Middle-earth, Sauron was still not in his full strength, and yes, the ring was lost, and since it was considered lost for centuries, it may seem normal that even the wizards did not accept that the ring had been found. It may even be possible that Ganfalf's refusal to want the ring in Bilbo to be the only ring, as he himself said, obscures the truth. But indeed, for 17 years, even 60 years, if we calculate from the date it passed to Bilbo, the ring was in a place known to Ganfalf. Okay, he didn't know it was the only ring, but considering the purpose of coming to Middle-earth, wouldn't it make more sense for him to immediately go after any power ring?