I think that one has to think what it means to speak of by 'mysterious', and whether it means that questions are difficult, or simply that areas of thought are completely fuzzy. A short while ago I had a thread titled, 'Can the philosophical mysteries be solved at all? The central philosophy mysteries I drew attention to were the existence of God, free will and life after death. I am not saying that people cannot come up with any answers to these questions, but simply that it is hard to establish definitive answers. My own thread became fairly long, and I am not sure that any clear answers were established. If you wish to read that thread you could scroll back a couple of pages, as it is recent, or look in the 'search' engine on the site. Or, you may wish simply to see what fresh answers anyone comes up with in response to your question.

You are new to the forum, so I welcome you and hope that it works out well for you. I have no idea of where you are coming from in terms of philosophical background or interests. I say that because this will partly determine how you think about the 'mysteries' in philosophy. There are so many different thinkers and perspectives, and I believe that you will find some who do not believe that there are any mysteries and that empirical methods can enable us to think through most problems. I can see where they are coming from, but at the same time, I do still believe that there are no easy answers. Language is important, and clarity in this can help untangle some philosophical knots. On the other hand, I do still believe that apart from analysis, which is useful for clear thinking, the other side of this is contemplation, which involves allowing imagination, in exploring some of the deepest and puzzling aspects of existence, life and death.

I forgot to press the arrow, so I am doing that now, so that you are notified of my reply.

I would turn the question upside down: is there any topic that isn't ultimately mysterious? If you go back to the concepts, words, ideas that we use to explain anything, and then back again to explain the explanations, you'll end up on unexplained things, whatever you start from. This means that, whenever we think we understood something, it's just an illusion.

Can philosophy be mysterious? — Dovidas Sneideraitis

Well, let's say philosophers can be, but philosophy shouldn't be. When mention is made of "mystery" I tend to associate what's being referred to as something only those with special knowledge, training or insight can understand. One has to be an initiate to understand mysteries (like an initiate of one of the ancient mystery religions).

Can philosophy be mysterious? — Dovidas Sneideraitis

I suppose it must be "mysterious" to non-philosophers. At the very least, however, philosophy is (strives to be) the art of demystification.