m_1 is convex; Therefore, r_1 is concave. Therefore A_1 consists of a mixture of constant (z) and concave (1r_11). The DOP rules require the argument of norm to be affine, which A_1 is not.Therefore, CVX does not allow constraint_2 to be formed.
However, because I don’t know how constraint_2 is used in your problem, I can’t say for sure that the problem is non-convex. Nevertheless, until you show your problem (which you have not shown it its entirety) is convex, I will assume it is not.