I bought the same guy and didn't get a work permit. I waited a month or two as he played for the under 21 Chilian team then offered him a new contract.
I think on the 2nd attempt of offering a new contract he got a work permit.
Same happened with Eddie Johnson, I had to loan him out to lyon (who played him once) for a season until he'd played for the USA national team enough to secure a work permit. Now he's just a back up target man as I had to sign Zigic (if I remember rightly) while he was MIA.