Leash of life vs Embers arcane ability damage

[HaveFunPlaying]

Game between HaveFunPlaying vs NickleBolus

Leash of life on board with Isadora Stormrage adjacent to Hero.
On Turn 7, I played Embers of the Just on Isadora, I understand she doesn't get fire damage because of leash of life. However when I destroyed ember, I targeted her with embers for ability damage while not being attached to her but she was still immune.

I would like to get some clarification on this. Thank you.

[Shadow Era]

Leash of Life - "While an ally is adjacent to your hero, that ally has immunity to enemy attachments and +1 health and its abilities cost 2 less resources to activate."
Embers of the Just - "Attach to target opposing ally and that ally is set ablaze. If Embers of the Just is targeted and destroyed on your turn, it is returned to your hand and target opposing ally takes 4 arcane damage."

So I assume the Leash and Isadora is on the enemy side...
When you cast Embers on Isadora: she is immune because of Leash.
Destroy Embers and target Isadora: she is still immune to enemy attachments, even if it is not currently attached, it is still a card type "Priest Ability - Attachment"

Perhaps in the future there will be other cards like: "Attach to target opposing ally. On each of its controllers turns, allies adjacent to it take 1 damage." Leash will still prevent this attachment damage to the hero-adjacent ally, even if it is not attached to that ally.

Hope that makes sense!