Vaal Clarity Bug

I'm fairly certain the Vaal Clarity skill should not have a chance to not apply the buff on skill use. There are times when using Vaal Clarity results in no buff, but consuming all charges (making the skill unavailable). I've tried to reproduce and determine what events lead up to the bug, but I've been unable to pinpoint the cause (though I am able to reproduce this issue quite often).

It's my first bug report, so I'm not sure what else would be helpful.

If you get stunned while casting Vaal skills you fail the spell and also lose the souls.

Maybe this is what happened?

I will try to pay closer attention to see if that is happening what is happening.