question: hyper parameters not restored while resuming training
context: I call save_hyperparameters() in __init__(), and all hyper parameters sent to PL model are saved to checkpoint file. However, when i resume training from a checkpoint(call trainer.fit(..., ckpt_path=checkpoint_file_path)), the hyper parameters are not restored from checkpoint file and all of them keep initial values.
answer: hyperparameters are not restored by default because it allows users to update them if they want, using the checkpoint, while resuming.
  you can do this:
  model = LitModel.load_from_checkpoint(checkpoint_file_path)
  trainer.fit(model, ..., ckpt_path=checkpoint_file_path)