Season chuck roast all over with salt, pepper and garlic powder
Select "Saute" function on Instant Pot. Heat olive oil. Sear seasoned chuck roast on both sides. Remove roast to a plate. Add onion, carrots, celery, mushrooms and garlic; saute until fragrant, 2-3 minutes.
Add tomato paste and toss with vegetables to coat; cook for 2-3 minutes to caramelize (do not burn).
Add red wine and cook for another 3-4 minutes, to reduce slightly and concentrate flavor.
Add broth, thyme and bay leaf to pot. Place chuck roast back in pot. Cover and seal. Cook under high pressure for one hour.
Let Instant Pot naturally release pressure for 20 minutes, then release remaining pressure.
Remove pot roast from pot. Stir together arrowroot starch and water to dissolve starch; then stir into sauce in pot to thicken.
At this point, you can serve the pot roast, or let it cool down and refrigerate until ready to serve. When ready to serve, slice pot roast into serving pieces, removing any extra fat. Skim any fat off top of the gravy. Reheat pot roast in gravy over gentle heat.