Scorching Ray Totem's Exposure is unaffected by 'Exposure you inflict applies an extra -%'

Per title, the effect of Exposure from Scorching Ray doesn't appear to be modifiable when inflicted by a totem.

Test 1: demonstrating Scorching Ray's bugged behaviour
Scorching Ray: Fire Exposure applies -25% to Fire Resistance
Fire Mastery: Fire Exposure you inflict applies an extra -5% to Fire Resistance

Testing target is Garukhan, Queen of the Winds, an enemy with 30% elemental resistance (when in Act 9).

Scorching Ray cast by the player causes the target to become neutral to fire damage (0% resistance). Scorching Ray cast by a totem causes the target to remain resistant to fire damage (>0% resistance), despite having the Fire Exposure debuff visually. Video (youtube).


Test 2: confirming this is a Scorching Ray problem and not a totem problem
Frost Bomb: Cold Exposure applies -15% to Cold Resistance
Tulborn x2: Cold Exposure you inflict applies an extra -24% to Cold Resistance

Frost Bomb cast by the player causes the target to become vulnerable to cold damage (<0% resistance). Frost Bomb cast by a spell totem has identical behaviour. Video (youtube).

Thank you for this testing, upvoting for visibility, I'm one of ... one? person playing scorching ray totems XD