The problem with the "flicker strike" skill

Good afternoon, there is a problem with the "flicker strike" skill. Doesn't reload instantly when there are two minimum frenzy charges (from the tree and the ring). Is this the way it's designed or some technical defect?

Minimum frenzy charges cannot be consumed. So assuming this was on your ring, it would not have helped.

I have only played flicker strike once, playing cold flicker raider with terminus est. So I had raider ascendancy, flicker, terminus est and ice bite which seemed to sustain flicker for me. There are also fire-variants which use Oro's. Blood rage also helps while mapping.