Same issue here, sound and music audio plays but not dialogue. Also, after playing any cutscene, all further dialogue audio (NPC interaction) is muted until the game is restarted. Lots of people here with the same issue, also checked the US forums and Reddit. Disabling the addons, deleting WTF and cache folders as well as scanning and repairing did nothing. It’s a bug.
Unfortunately it’s game breaking, literally. 
I’ve stopped playing the campaign on all characters until it’s fixed, completely destroys the experience.
EDIT: It’s acknowledged. Give it a few days, it’s getting fixed. I suggest avoiding the campaign until then.