why "buy/sell" marker is not in the right position?

[bilibili]

Hi Guys,
My data feed is hour bar, 6 bars per day. But it seems buy/sell marker is not in the right position sometimes.
Some of the marker is in the right position, but some of them not. I've no clue about it.

Like the picture below,
2020-05-21T23:00:00, BUY CREATE, 3375.00.
Buy order should be placed on the hand drawn red arrow (2020-05-21T23:00:00), But it was moved behind couple K lines.

data
3376.0,3386.0,3373.0,3384.0,269762,14987,0.0,2020,5,20,10,0,2020-05-20 10:00,3.780170763331913e-40
3384.0,3388.0,3379.0,3386.0,268820,8959,0.0,2020,5,20,11,15,2020-05-20 11:15,3.766970531797973e-40
3385.0,3387.0,3375.0,3381.0,266271,13117,0.0,2020,5,20,14,15,2020-05-20 14:15,3.731251433942334e-40
3381.0,3384.0,3376.0,3376.0,268181,10815,0.0,2020,5,20,15,0,2020-05-20 15:00,3.758016234610938e-40
3370.0,3386.0,3370.0,3379.0,266282,13071,0.0,2020,5,21,22,0,2020-05-21 22:00,3.731405576773409e-40
3380.0,3382.0,3375.0,3375.0,266156,6290,0.0,2020,5,21,23,0,2020-05-21 23:00,3.72963994070836e-40
3376.0,3394.0,3376.0,3384.0,262578,14631,0.0,2020,5,21,10,0,2020-05-21 10:00,3.679501481654818e-40
3384.0,3392.0,3381.0,3390.0,261784,9748,0.0,2020,5,21,11,15,2020-05-21 11:15,3.668375171848079e-40
3390.0,3407.0,3382.0,3405.0,257708,23010,0.0,2020,5,21,14,15,2020-05-21 14:15,3.6112582464421996e-40
3405.0,3406.0,3394.0,3403.0,255225,19957,0.0,2020,5,21,15,0,2020-05-21 15:00,3.5764640055730144e-40
3405.0,3423.0,3403.0,3420.0,250612,23267,0.0,2020,5,22,22,0,2020-05-22 22:00,3.5118221074137106e-40

class data_feed_future(btfeed.GenericCSVData):
    params = (
        ('dtformat', '%Y-%m-%d %H:%M'),
        ('datetime', 12),
        ('open', 0),
        ('high', 1),
        ('low', 2),
        ('close', 3),
        ('volume', 5),
        ('openinterest', -1) 
    )


if __name__ == '__main__':

    cerebro = bt.Cerebro()


    data = data_feed_future(dataname=data_file_dir + '\\' + ticker + '.csv',compression=60 ,timeframe=bt.TimeFrame.Minutes)
    cerebro.adddata(data)
    cerebro.addstrategy(strategy_under_test)

    # Set our desired cash start
    cerebro.broker.setcash(startcash)
    # Set the commission - 0.1% ... divide by 100 to remove the %
    cerebro.broker.setcommission(commission=0.002)
    # Add a FixedSize sizer according to the stake
    cerebro.addsizer(bt.sizers.FixedSize, stake=1)
    results = cerebro.run()  # run it all
    cerebro.plot(style='candlestick')