Problem: Illegal operation: {real affine} - {invalid}

As I wrote above,

Also, use Mosek as solver if you have access to it, otherwise see 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 .