If you have Mosek available, specify it as solver. Otherwise follow the directions 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 .
And make sure all the non-zero input data is within s small number of orders of magnitude of 1. Change units if needed to accomplish this.
if the model is still reported as unbounded, follow the advice at
Debugging unbounded models - YALMIP , which also applies to CVX.