i have the same issue here
my battle.net ID is CrazyMage#266145
i even open account on activision in order that maybe it will work
and it didnt work.
so what now????
I've got the same issue recieved the email this morning but just keeps giving that error.
I have emailed Asus but no reply from them yet. I linked my battle.net account to Call of duty, and it takes me to the page asking for code and platform. I enter the code and selected "battle.net" as platform, but resulted in a black screen. Upon refreshing and entering the code again, it gave me an error that "The code has already been redeemed". I tried another just in case, but still the same error. I only got today to play since my exams starts next week, I hope to get some help soon.
Having the same error on my end. Bnet account is liked properly and everything.