much of the literary fiction genre. But maybe what I'm thinking of as straightforward mainstream actually is in the literary genre and I'm not recognizing it. But I do tend to think of literary fiction as the kind of highfaluting thing that I don't like. I recently read a short story in some one of the mainstream magazines (Good Housekeeping, maybe) that was their contest winner. That was apparently intended to be a literary piece by your definition, as things happened and the essential problem was never resolved.
I read a lot of science fiction, any number of mainstream novels, likewise mysteries, historical novels, and so on. It's easier to state that I don't generally read westerns or romance.
Straightforward mysteries do tend to solve the problem. One of my gripes, not really connected to my initial complaint here, is that 95% or so of mysteries are part of a series of some kind. I very much prefer stand-alone novels of all kinds, although there are exceptions in that I do love the Janet Evanovich series and a couple of others.
Anyway, I've also been noticing this problem in science fiction lately. Especially in books that are really science fiction but get published as mainstream novels, such as The Age of Miracles, which I liked a lot until the ending, which felt like she'd written herself into a corner and had no idea how to write her way back out.