Solar Storm + Blessing of the stars

[Lava Floor]

I cast Blessing of the stars on Solar Storm, But the 100% critical rate only work on first shoot.
Is it bug? or the effect of Critical rate buff can't effect the repeated Solar Storm?

Video：
https://www.youtube.com/watch?v=wCMGgt94nvM

The Solar Storm basic damage is 22.
The Fallen king defense is 25%.(I don't have decreasing defense gears)
Repeated Solar Storm damage is 22 * 0.5 * 0.75 = 8.25 (8)
The video show Blessing of the Stars Critical buff doesn't work on the Repeated Solar Storm.