DIAGNOSIS You're overloading or under-preheating. Soggy bottoms mean the hot air isn't circulating underneath the food, so it's steaming in its own moisture instead of crisping.
FIX First, always preheat. Run the Air Fry function at your target temp for 3-5 minutes with the empty basket inside before adding food. Second, don't fill the basket more than halfway. Food needs space between pieces. Use the crisping tray (solid metal sheet) for things that release a lot of fat or moisture, like chicken wings—it catches drips and lets the food sit above the pooled liquid.
IF THAT DIDN'T WORK Your food might be too wet. Pat proteins and veggies absolutely dry with paper towels before adding oil and seasoning. A light, even coat of oil is crucial—it helps conduct heat and crisp the surface.
HEADS UP The "Shake" reminder is a suggestion, not a magic fix. For truly even cooking, you need to manually rearrange food, moving items from the center (hotter) to the edges (cooler). Just shaking often leaves bigger pieces nestled together in the middle.