T.W.
Have you checked with the people who re-upholstered it? Maybe there is a problem with the shipment of the fabric or something. It may be the actual stuffing from the old couch that needed to be cleaned before it was re-upholstered. They may be able to give you some advice. I cannot imagine that being in a studio for only a month would have caused a musty smell you cannot remove.
Other options may be to use some expensive perfumes or something of that nature. They tend to hang around for quite a while. I have also used Lysol before which is good for killing any germs that may be in the couch. I have never had luck with Febreeze - EVER. I lasts as long as airfreshner, which isn't long.
Good luck!