Impossible to answer without reproducible problem. But you should consider all values to be meaningless if CVX reports Failed.
For this problem, you should use Mosek as solver if it is available to you. Otherwise, follow the instructions at CVXQUAD: How to use CVXQUAD's Pade Approximant instead of CVX's unreliable Successive Approximation for GP mode, log, exp, entr, rel_entr, kl_div, log_det, det_rootn, exponential cone. CVXQUAD's Quantum (Matrix) Entropy & Matrix Log related functions .