Life sometimes cannot be recharged by Eternal Youth

I have allocated Eternal Youth and Zealots Oath.

As a result, I should only have life recharge.

I usually spam my storm brand with right click and cost life instead of mana because of Blood Magic.

However, sometimes my life cannot recharge back to full after casting a brand.

I tested in my hideout and in maps, surrounded with mobs.

Hideout: If my life suddenly cannot recharge and stuck in certain amount of life (like my attached image), then I cast another spell, like marks or shield charge, my life will recharge back to full. If I don't cast anything, nothing happens.

Maps: If my life suddenly cannot recharge and stuck in certain amount of life, once immortal call triggerred by CWDT, cast another spell or turn off some auras, my life will recharge back to full.

I checked my in-game info that I should have 2000+ life recharge.

The life cost of one storm brand should be 64 per cast.

Please let me know if you need further clarification or you found the reason why I can't recharge my life to full.

Started happening to me too the moment i switched to predictive.