IndexError when using DataHandlerLP

Hello,

I am encountering an UnsortedIndexError when using DataHandlerLP in Qlib. It seems to be related to MultiIndex not being lexsorted. Could you provide guidance on how to resolve this issue?

UnsortedIndexError: 'MultiIndex slicing requires the index to be lexsorted: slicing on levels [0], lexsort depth 0'

handler = DataHandlerLP(
    data_loader={
        "class": "QlibDataLoader",
        "kwargs": {
            "config": {
                "feature": market_info,
                "label": ["Ref($close, -2)/Ref($close, -1) - 1"]
            },
        }
    },
    instruments="csi300",
    infer_processors=[
        {
            "class": 'RobustZScoreNorm', 
            'kwargs': {
                'clip_outlier': True, 
                'fields_group': 'feature', 
                'fit_start_time': '2009-01-01', 
                'fit_end_time': '2019-12-31'
            }
        },
        {
            'class': 'Fillna', 
            'kwargs': {
                'fields_group': 'feature',
            }
        },
    ],
    learn_processors=[
        {"class": 'DropnaLabel'},
        {
            "class": 'CSZScoreNorm', 
            'kwargs': {
                'fields_group': 'label',
            }
        },
    ],

)

Thank you.

Start by reproducing the supplied DataHandlerLP configuration and trace the MultiIndex slicing that raises UnsortedIndexError. The issue names no source file or test, so locate the relevant Qlib data-handling entry point first; done would require a documented or verified resolution for the lexsort failure.