Hi,
did you follow this guide: Object Detection with TensorFlow Lite Model Maker 9
?
One problem that might happen on your images is that they are too big and when the tool tries to crop it for the proper input size it removes by mistake the ducks from it (that my random guess)
On the tutorial I mentined there’s a specific link on preparing your own data and that might give you some insights on how to fix this.
hope it helps