Shaper of Flame and Echoes of Creation not self igniting.

Friend has been using Echoes of Creation+Shaper of Flame and has noticed he hasn’t been self igniting. I was wondering if this was because Echoes didn’t count as a ‘hit’ but after equipping Mokou’s Embrace we found that the helmet was able to ignite(25% of the time). Why wouldn’t shaper of flames allow the self ignite to take place normally?