YOLOV4 AP all zero in custom dataset

Refer to SSD: custom tlt training result in AP:0 for all my classes - #6 by Morganh

Please modify your spec, set to lowercase class name.
For example,
target_class_mapping {
key: “Car”
value: “Car”
}

to

target_class_mapping {
key: “car”
value: “car”
}