text: Title: Anyone successfully run a US benchmark yet? There seem to be a bug with US version, instrument variable got evaluated to NAN. 
  Body: ## 🐛 Bug Description
  
  <!-- A clear and concise description of what the bug is. -->
  
  ## To Reproduce
  
  Steps to reproduce the behavior:
  
  1. take any yaml file under examples/benchmark. I'll take workflow_config_lightgbm_Alpha158.yaml for example. 
  2. Change all fields from china version to US version:
  2.1 change (provider_uri: "~/.qlib/qlib_data/cn_data")  to  (provider_uri: "~/.qlib/qlib_data/us_data")
  2.2 change( region: cn) to  (region: us)
  2.3 change (market: &market csi300) to (market: &market sp500)
  2.4 change (benchmark: &benchmark SH000300) to (benchmark: &benchmark ^GSPC)
  
  3. Run 
  qrun  workflow_config_lightgbm_Alpha158.yaml
  
  
  ## Expected Behavior
  
  AttributeError: 'float' object has no attribute 'lower'
  
  Upon closer debugging, the instrument variable was evaluated to Nan. 
  
  
  ## Screenshot
  
  <img width="1045" alt="image" src="https://user-images.githubusercontent.com/1435138/215260135-671ad6bc-690e-4651-9314-4ecf138ae5b2.png">
  
  ## Environment
  
  **Note**: User could run `cd scripts && python collect_info.py all` under project directory to get system information
  and paste them here directly.
  
  Windows
  AMD64
  Windows-10-10.0.22621-SP0
  10.0.22621
  
  Python version: 3.8.15 (default, Nov 24 2022, 14:38:14) [MSC v.1916 64 bit (AMD64)]
  
  Qlib version: 0.9.0.99
  numpy==1.23.5
  pandas==1.5.2
  scipy==1.9.3
  requests==2.28.1
  sacred==0.8.2
  python-socketio==5.7.2
  redis==4.4.0
  python-redis-lock==4.0.0
  schedule==1.1.0
  cvxpy==1.2.3
  hyperopt==0.1.2
  fire==0.5.0
  statsmodels==0.13.5
  xlrd==2.0.1
  plotly==5.11.0
  matplotlib==3.6.2
  tables==3.8.0
  pyyaml==6.0
  mlflow==1.30.0
  tqdm==4.64.1
  loguru==0.6.0
  lightgbm==3.3.3
  tornado==6.2
  joblib==1.2.0
  fire==0.5.0
  ruamel.yaml==0.17.21
  
  
  ## Additional Notes
  
  