Ailith's Chimes Not Working as Description Reads

I'm using this Lineage support on my basic quarterstaff strike. Usually, I will try to get it up to 10 combo so that it is a 100% chance to generate the power charge. Sometimes I run out of monsters though and end up at 8-9 combo. This should be an 80-90% chance to still work, according to the tooltip. However, it almost always fails. Like WAY too often for it to just be bad RNG. There seems to be something not working correctly with it.

Appreciate yall looking into this!