Bought my daughter the new indoor Blink camera and when she opens the app and goes to live video there is no talk button for 2 way audio. She does have audio turned on in settings.
Welcome to the forums! Most likely either the camera or the sync module needs to update its firmware. Nothing she can or needs to do as the update should happen within a day or 2. If it doesn’t she can call tech support and they will push it to her. Good luck and let us know how you make out.