After 3 hours on a machine with 2 gpus, I reached this value
model_lib_v2.py:708] {
 'Loss/classification_loss': 0.28390533,
 'Loss/localization_loss': 0.26865262,
 'Loss/regularization_loss': 57.277615,
 'Loss/total_loss': 57.83017,
 'learning_rate': 0.0}

I researched and the zero learning_rate means that there is nothing to learn, but the train with model_main_tf2.py don’t end 
Please any help is appreciated.
Thanks