No best model is saved in checkpoints.

[ShuhuaGao]

If I set the callbacks argument in SupervisedRunner.train as follows:

callbacks=[CheckpointCallback(
        logdir=f"log/{timestamp}/model", loader_key="valid", save_best=True, topk=1)],
num_epochs=10,

No model.best.pth is produced. There are only two model files available: model.0010.pth and model.last.pth.