Make sure the bottom of your pot is clean after sautéing the vegetables before adding the rice. Some models of Instant Pot or other brands are more sensitive to burn warnings when cooking rice. If necessary, add a bit of liquid and scrape up any bits from the bottom of the pot before adding rice. One minute on High Pressure is the correct time. But that doesn't mean the chicken only cooks for 1 minute. Before the pot reaches high pressure and begins to count down the 1 minute stated, it's steaming and cooking inside the pot for anywhere from 10-15 minutes. Once the pressure is released, it rests inside the pot for 5 minutes more, during which time it continues to cook and also relax. The chicken breasts should be just cooked through and juicy, not shreddable. The timing in this recipe is built for 8 ounce chicken breasts, thawed fully if frozen. If you have larger chicken breasts, halve them horizontally to ensure they are cooked through in time.