Client: 1.1.11 (Steam PC)
When using a plethora of different Fire based spells on my Draconic Origin (obvious red/fire) Sorcerer I found that most spells didn't work correctly with elemental affinity. In my previous playthrough (post Sorcerer update) I had a Shock Arcanist Wizard and I do remember that working with each ray of Scorching Ray so that may be something to look at.
Firebolt: Works, except if you twin cast it. Then it will work for only one of the targets.
Scorching Ray: Works for only the first ray, regardless of whether you're hitting the same target with each ray or just one.
Fireball: Works correctly, hits all enemies hit by fireball.
Burning Hands: Did not test