This is one of the few classes they have confirmed to be not working on.

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Will all 5e Classes be available at launch?

NickP: Yes, all classes from 5e Player’s Handbook will be included at launch. In Early Access you’ll be able to play as a Cleric, Fighter, Ranger, Rogue, Warlock or Wizard.

Custodian of the Baldur's Gate 3 Datamining thread