hi,team:

    my dag is 1 minute schedule,one parts dag state is success,but tasks state is not yet started in a dag:

![image](https://user-images.githubusercontent.com/41068725/116344664-357d8780-a819-11eb-8010-c746ffdfdbcc.png)


   how can to fix it?
airflow/settings.py
"""Properly close pooled database connections"""
    log.debug("Disposing DB connection pool (PID %s)", os.getpid())
    global engine
    global Session
    if Session:
        Session.remove()
        Session = None
    if engine:
        engine.dispose()
        engine = None
def configure_adapters():
    """Register Adapters and DB Converters"""
    from pendulum import DateTime as Pendulum
    try:
        from sqlite3 import register_adapter
        register_adapter(Pendulum, lambda val: val.isoformat(' '))
    except ImportError:
        pass
    try:
        import MySQLdb.converters
        MySQLdb.converters.conversions[Pendulum] = MySQLdb.converters.DateTime2literal
    except ImportError:
        pass
    try:
        import pymysql.converters
        pymysql.converters.conversions[Pendulum] = pymysql.converters.escape_datetime
    except ImportError:
        pass
def validate_session():