When Googling the store page, it says:
Notice: Night Run is no longer available on the Steam store.
So I guess it makes sense you can't search for it.
Yeah, I’ve noticed this happens when steam removes a game. They need to do a Netflix sort of thing and be like “We know this exists, but we don’t have it”
I've never had the feeling that it was particularly bad. In your case it seems to be that the game Night Run was removed from the Steam Store, which is why it's excluded from the search. Which isn't great when the store page still exists...
The only thing that I don't like about the search is that the tags are crowd-sourced so you get a lot of games tagged as genres they aren't.
i hate how you can only filter price by 5's, so if you have like 17 bucks in your steam wallet you have to sort by 20 and ignore like half of the options