That's another proof that "problematic" may be used as a noun. I must admit that it is not very common and that most natives don't know that it may be used that way. However, it is thus employed in papers on epistemology and skepticism that are published in international journals of philosophy.
Cheers
P.S.: it seems to be the same as what happens in Spanish. The term "problemática" is the feminin form of the adjective, but may be used as a noun.