cast on ability not turning on?

Hello,

This is a new issue i have ran into where my cast on ability is not turning on. i meet all the stat requirements and i even tested with 2 different lower level gems. Visually in the skill screen you can see its turned on, however it doesnt remove any spirt from my reservations and the % that shows how much energy gained is not appearing. i respect my characters stats just to double check and and that wasnt the issue. Ive used this same cast on crit with this character like yesterday and it was fine, but today this character it wont work on. i switch a different character i have, and they can use it perfectly fine. Same set up and everything, just different ascendancy.