Those that believe that understanding of the world is possible must also believe that understanding of “understanding” is possible. The problem with “understanding” is, however, that something must be assumed for something to be explained, whereof the assumption can’t be explained, meaning that “understanding” can’t be explained. And, if “understanding” can’t be explained, then it is neither possible to understand the world.
The problem that the world is unintelligible is thus fundamentally not a question about the world itself, but about that it is impossible to “understand” fundamentally. “Understanding” can be phrased in many different contexts, but a fundamental understanding, including understanding of understanding, is impossible. The question whether the world is understandable (ie, intelligible) or not can thus not be answered, ie, is beyond reach for words.
The problem to understand the world is thus created by words themselves, and lacking a solution per definition. This, I would say, is the problem with the world.