Turn Instant Pot to Saute’. When HOT, add butter until melted. Combine flour and beef and add to pot. Add garlic. Stir occasionally until all sides brown. It’s OK if the drippings stick, just don’t allow to burn.
When brown, add beef broth and stir until dripping dissolved. Add BBQ sauce, salt and pepper, bay leaf, and rosemary. Stir to mix.
Add potatoes, onions, carrots and mushroom. Mix together. Secure lid and select stew/meat setting for 35 minutes. When done, allow natural release.