How did Hades not find out that Hercules was alive in 18 years?

I've noticed what seems to be a plot hole in the Disney version of the movie Hercules, and I'm hoping someone can fill it in with a logical explanation!

So in the beginning of the movie, we have Hades coming to the celebration of Hercules' birth. It is very clearly established that he does not like Zeus, at all. But Zeus seems happily oblivious; he's glad his brother is there, he jokes around with him, tells him he should stay at the party longer and not work so hard. So we've established, then, that Hades does not like Zeus at all, but that Zeus doesn't know this, and however often they see each other, he likes his brother and thinks they have a good enough relationship to invite him to the celebration of his son's birth.

Fast-forward to the scene on Mt. Olympus after Pain and Panic have just failed to kill Hercules. Zeus and Hera wake up to find baby Hercules missing from his crib...

It was tragic. Zeus led all the gods on a frantic search. But by the time they found the baby, it was too late. Young Herc was mortal now. ... But Zeus and Hera wept because their son could never come home. They'd have to watch their precious baby grow up from afar.

Okay. So, I am totally able to accept that "all the gods" here refers to all the gods on Mt. Olympus, which would be all of them except Hades. So Hades did not participate in the search for Hercules—fair enough, I buy that.

However. At some point, one of the gods on the search found Hercules ("But by the time they found the baby, it was too late.") At this point, all the gods on Mt. Olympus (so, all except Hades) now know that Hercules has been found, and Zeus and Hera watch baby Hercules with his new mortal parents, and are sad that he can't come back to Mt. Olympus.

At some point during the next 18 years, no one talked to Hades about this?

I find this very, very hard to believe. All the other gods don't like him; fine, I can accept that they wouldn't have told him (or spent much time with him). Hades doesn't leave the Underworld often, so he wouldn't have spent much time on Mt. Olympus and heard it by accident—I can buy that too.

But Zeus is his brother. He's just had a baby, and a huge party celebrating that baby's birth where he invited his brother and tried to get him to stick around longer. If you have a brother who you care enough about to make jokes and invite him to the baby's party etc.... Then you're going to go visit that brother and tell him in person that your baby has been kidnapped and lost his immortality, and that you've lost your only chance to ever raise your son. I think you're going to go tell him pretty darn quick, actually, because you're upset and grieving and want your family's support. But setting speed aside—at some point within the next couple of days, you're going to tell him. Of course you are. Who wouldn't?

I just find it very hard to believe that Hades managed to go 18 years without hearing the slightest whisper of the most awful tragedy to rock Mt. Olympus since...well, probably the Titans. There was only one baby god up there. This would have been a pretty big deal. Yet somehow Hades manages to get through the next ~18 years without finding out until Hercules rescues Meg from the River Guardian.

Someone want to plug this plot hole for me?