Last session, my Warlock was being attacked by a pair of Winter Wolves, and not doing well. I was able to get a little away, and cast Darkness to hide from them. My DM wasn't sure how exactly the wolves should handle this situation.
We know that it's impossible to see in magical Darkness unless you have something like True Sight. But one of the other players at the table was hesitant to say that the wolves should get disadvantage because the wolves have advantage on perception rolls using scent/hearing. I still would argue that while the wolves maybe can smell where my character is, it's not an exact science where the wolves know exactly where he is, they'd still need to have visual confirmation to make sure that they can hit him.
After all, a blind wolf in the wild is a dead wolf in the wild. While a blind wolf could perhaps smell a living creature, it's still going to have trouble targeting a creature that can move around, even if it's right next to it. A blind wolf could find a stationary object, like a dead carcass, and feed off it, but it's still going to stumble, run into things, and generally head towards false trails without visual direction.
While the wolf maybe could make make an ability check at our table, I would assume that would use up his action (as we play it, I'm not sure if that's in the handbook or not, I haven't looked at it yet), but he'd still have problems with making visual confirmation at where exactly the target is.