There is nothing to maximize unless your problem is feasible.You have now yet shown a reproducible problem which is feasible. You can not rely on randn in your code to provide a reproducible problem.
If you do formulate a feasible problem, then follow the advice in 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