Elixir of the Broken Circle not acting as true "Life Recovery from Flasks"

I'm not entirely sure as to whether this is a bug or intended, but I wanted to see if the "Recover 4% of life per Endurance Charge on use" was affected by the passive nodes on the tree and other flasks.

To test this I used a "The Sorrow of the Divine" to make my life recovery from flasks apply to energy shield.

While I had The Sorrow of the Divine active, I would use Blood Rage to lower my HP and ES, and use the Elixir Flask once to first generate Endurance charges. then I would once again use the Elixir to recover 12% of my life (and also presumably my energy shield), but only my life was recovered.

When I tested the same process but with a Forbidden Taste instead of the Elixir (because they have quite similar wording, "Recover xx% of life on use"), I was able to recover life and energy shield when I used the flask under the effects of The Sorrow of the Divine with no energy shield.

This would lead me to assume that flask nodes on the tree that provide "% increased recovery of life from flasks" work with the Forbidden Taste but not the Elixir?

Thanks for reading~