Initial hit of Firestorm not dealing damage

When I have Firestorm linked with Awakened Spell Cascade and Div Spell Echo, the initial hit of Firestorm deals no damage.


I don't know how to share the recorded gameplay that I was able to transfer onto my USB.



This is one of the recorded gameplay videos that I have.
https://www.youtube.com/watch?v=-DsgLKMsL0c