Tender Emberace won't proc with Coward's Legacy

I tested Tender Emberace while equipping Coward's Legacy and it's not applying any buffs to me.
If I made myself low life, it'll proc normally(with Coward's Legacy on).
I'm not sure if it's a bug, but Coward's Legacy should "count my character as low life" and when I'm low life Tender Emberace should periodically apply a buff to me right?