Diagnosis
You are overloading the basket or not preheating. Air needs to circulate freely around all food surfaces.
How to Fix It
Always preheat on Air Fry for 3-5 minutes. Use the provided air fry basket, not a tray. Do not stack food. Arrange in a single layer with space between pieces. Shake the basket halfway through cooking, as instructs.
If That Didn't Work
The upper heating element may be weak or failing. The air fry function relies heavily on radiant heat from that top element. If it's not reaching full temperature, performance suffers.
Heads Up
Pat food dry before air frying. Excess moisture is the enemy of crispiness. This is especially important for frozen foods like fries or wings.