Set multicooker on SAUTE function according to manufacturer’s instructions. Cook bacon 3 to 5 min. until crisp; remove from pot to drain on paper towels; set aside. Retain the excess bacon fat in pot.
Pat roast dry with paper towel. Brown all sides in multicooker, about 8 min. Remove from pot. Add potatoes, carrots, mushrooms, onion, garlic and 4 tsp (20 mL) thyme to pot. Saute about 5 min., until veggies begin to turn golden. Return roast to pot.
Whisk together broth, tomato paste and Worcestershire sauce. Pour over roast. Lock on lid. Cook on HIGH PRESSURE 1 hr., or until very tender. Manually release pressure according to manufacturer’s instructions before removing lid.
Transfer beef and vegetables to a platter; tent with foil. Strain juices in pot, returning them to the pot. Set to SAUTE again to reduce juices by half, about 15 min. Drizzle roast with reduced juices. Pour the rest into a gravy dish to serve alongside. Garnish roast with reserved bacon and additional thyme.
Add any leftover beef and veggies to homemade soups, such as barley.