MAISI load_unet func misses the load of scale_factor for finetune training

[shengzhang90]

Hi,

During the training with scripts/diff_model_train.py file.

Sometimes, the calculate_scale_factor func will output the result of "scale_factor=nan", could you please set and fix the "scale_factor" parameter in certain json file?

Also, for the finetune training, could you please load the "scale_factor" in load_unet func since you have save the "scale_factor" in the save_checkpoint func. Thanks a lot.