Hexblast not working properly

In Hexblast showcase video in-game, says it detonates every curse on the monster.

I was playing Monk Hexblast + Hand of Chayula with Whispers of Doom and found a lot of things not working.

First of all, the Enfeeble curse are not proccing with the Hand of Chayula, forcing me to use another curse.

Second, the Hexblast are detonating only one curse per cast, unlike they show in the video. It was supposed to detonate every curse on the target (and i presume it would gain a additional explosion for every curse?)

And lastly, i tried to solve the second problem using the "Spell Echo" support gem, but it's not echoing the hexblast, so it's not working properly as well, since the expected was "one hexblast cast = 2 explosions (since the target got 2 curses)", but the echo dont work at all.