Ok, I found what is different; I was using the Dataset derivative as follows:
# dataset class for the data
class Data(Dataset):
    def __init__(self):
        pass
        
    def __len__(self):
        pass
    
    def __getitem__(self, idx):
        return idx

I was expecting it to return the indices I could use to subset the training set, however the weighting didn’t work. It DOES work with the TensorDataset, so I will use it instead. Thank you for your help!