Select Sauté on the Instant Pot and add oil to pot. heat 2 min.
Once hot, add the potatoes and cook, stirring for 1 minutes.
Then add the carrots, celery, onions and garlic and cook for another 2 minutes, stirring frequently.
Add the chicken, corn, chicken stock, sauce, pepper and nutmeg and give everything a stir, deglazing the base of the inner pot.
Press cancel and secure the lid, then select Pressure Cook and set the time for 8 minutes.
When the cooking program finishes, perform a Quick Pressure Release then remove the steam.
Remove the chicken from pot; place on plate and shred using 2 forks.
In a small bowl, mix the cornflour and water until blended, then add to pot along with the cream and shredded chicken; mix well.
Press cancel and select Sauté again, and sauté until the chowder is thickened and heated through, stirring constantly.