Bad accuracy when training on custom data

[codingzebra33]

Hi, I get bad training results when using YOLOX-s.
I have a custom dataset with 30 classes and approximately 500 images. Each image contains multiple class objects, so the dataset size should be enough. No matter what epoch and batch size I use, COCOAP50 is always around 0.30 and COCOAP50_95 is 0.40.
For the reference, I have used the same dataset to train YOLOv7 and YOLOv8 and the accuracy is close to 90%.

Any suggestions on how to make YOLOX training better? (Apart from the basics - epoch size, batch size, dataset augmentation)