DIAGNOSIS You're overloading the basket or using too much oil. Air needs to circulate under the food.
FIX Do not stack food. Use a single layer. Pat proteins and wet veggies completely dry before cooking. Use an oil sprayer, not pouring oil. For frozen foods, increase temp by 25°F and add 3-5 minutes.
IF THAT DIDN'T WORK Check that the rear exhaust vent is not blocked by a wall or cabinet. Poor airflow cripples performance. Ensure the basket is fully clicked in; a poor seal affects internal air circulation.
HEADS UP The non-stick coating on the basket can wear. A damaged coating causes more sticking, which leads to overcrowding as you try to avoid mess. Replace the basket if coating is flaking.