Whispess, Weavess and Brewess each state that their abilities increase each time one of the others is played. Whispess: Tribute, and Weavess: Incantation, are both clearly whispess and Weavess cards, but do not increase this count.
Never thought of this as a bug. Whispess is a not the same card as Whispess: Tribute.
Note that the card text says "... you play Weavess...", not "... you play a Weavess card..". Probably not the best explanation, but my point is that the Legendary Crones are different cards than their Epic versions.