Add water as necessary.Note about thickening stews and soups in the Instant Pot: Use care when thickening your soups and stews. In fact, you should never add corn starch (or too much flour) when cooking under pressure. Instead, cook your soup or stew and release pressure completely before adding your thickening agent.
https://lostmycookbook.com/beef-stew-instant-pot-style/ -- January 27, 2021