查询分钟级别数据失败

pdd=ContextInfo.get_market_data_ex(['close'],['002156.SZ'],period="60m",count=250)

为什么返回的是日线数据？

1分钟
df = ContextInfo.get_market_data(['close'], stock_code = ContextInfo.get_universe(), skip_paused = True, period = '1m', dividend_type = 'front')
60分钟
df = ContextInfo.get_market_data(['close'], stock_code = ContextInfo.get_universe(), skip_paused = True, period = '1h', dividend_type = 'front')