Decaying Hex ignoring any amplifiers for chaos damage

I tested both with items and passive tree. The gem clearly has chaos tag, and it's chaos damage (over time), but it ignores any chaos passives, and any bonuses from items to chaos. The tooltip doesn't change whatever you're getting.
Honestly, it ignores everything at all, including spell damage, duration, other gems, whatever. No matter global it is or not.
Good luck to gather some 500 int for it to do at least 300 damage per sec, and even then with this bug it's laughable, especially compared to millions of damage builds or even its own same row lvl1 alternative, that can hit.
Changing it from 30 to 60% scaling looks like a joke.