Per the wiki, the Essence Chamber in the Wizard Guild in Ta'Vaalor is a workshop.

Using the sense verb reveals this room isn't a workshop:

You study your surroundings and use your keen knowledge of the arcane. It quickly becomes evident that this room is not a magical workshop.

Is this a mistake or is the workshop a different room in this guild?

Ah, thanks for the heads up. Narost didn't mention anything about a puzzle nor did the Wiki.