First step for you: Have you proven this is a convex optimization problem?
Per the link, “being sure” it is convex is insufficient. If I had a nickel for every time a poster on this forum was sure their problem was convex, but it really wasn’t, I wouldn’t be rich, but I would have several dollars. If you are actually using some type of algorithm which solves a sequence of convex optimization problems in order to solve a non-convex optimization problem, you need to clearly state what those convex optimization problems are.
The first constraint can be rewritten as
square_pos(norm(Wr,'fro')) + square_pos(norm(Wc,'fro')) <= P
if wc were input data, the second constraint could be handled by multiplying through the LHS denominator, i.e, moving the denominator to the RHS. But apparently wc is not input data?