I think both Buber and Marcel distinguished between a problem and a mystery. For a problem, one has the answer; Lonergan would say: there are no further relevant questions on that problem; one has virtually unconditioned truth regarding that problem. Even though some truth can be discerned and affirmed regarding a mystery, there are always further important questions, more to be pursued and elucidated. As Karl Rahner argued, the ultimate mystery is Mystery itself, God.
Both in the case of problems and of mysteries, it is the knower–a subject and therefore, by that definition, subjective– who knows. When the knower asks the right questions and affirms the answers that thus emerge, objective truth is attained, no matter how partial. Thus, true subjectivity is objectivity.

The splitting of truth, virtue, and beauty adverted to by RiverC is made worse by a narrow definition of truth, e.g., reductionism or the refusal to acknowledge other paths to the truth–scientism eliminating common sense and transcendence, for instance; or any of the three degrading or eliminating the other two.