Turn Instant Pot® to High Sauté and let heat for about 1 minute. Add the bacon and cook until brown and crispy, about 5 minutes. Add onion and cook, stirring frequently, until onions become translucent, 2–3 minutes. Stir in potatoes, corn, water, thyme, and cayenne; season with salt and pepper. Place lid on pot and lock into place to seal. Cook on High Pressure for 10 minutes. Use Quick Pressure Release. Press Cancel. Empty pot into a large serving bowl; taste and adjust seasoning, if necessary.
Turn pot to Normal Sauté and stir in the cream and flour; cook, whisking frequently, until smooth and slightly thickened, 4–5 minutes. Stir thickened cream into soup. Serve, garnished with chives, if desired.