Cannot login to Activision Account: "Account Login Error"

[Conman1700]

Can't even play the campaign because this game requires you to login. After logging in with my Activision account which is linked to this Steam account, it errors out with

Account Login Error

Account could not be linked because that Activision account is already linked to a different account of the same type. If you believe this is in error, please visit https://s.activision.com/activision/ to view the account.

I've only ever had one Activision account and one Steam account (this one), and they're both already linked together. EXTREMELY frustrating not being able to play a $70+ game.

[Mizu]

have to unlink steam account and relink, for some reason it was using an older dated version of my steam account with a diff username, after relinking it worked for me.