airflow reschedule error: dependency 'Task Instance State' PASSED: False - airflow

Question

I have a customized sensor that looked like below. The idea is one dag can have different tasks that can start from different time, and take advantage of the built-in airflow reschedule system.
class MySensor(BaseSensorOperator):
def __init__(self, *, start_time, tz, ...)
super().__init__(**kwargs)
self._start_time = start_time
self._tz = tz
#provide_session
def execute(self, context, session: Session=None):
dt_start = datetime.combine(context['next_execution_date'].date(), self._start_time)
dt_start = dt_start.replace(tzinfo=self._tz)
if datetime.now().timestamp() < dt_start.timestamp():
dt_reschedule = datetime.utcnow().replace(tzinfo=UTC)
dt_reschedule += timedelta(seconds=dt_start.timestamp()-datetime.now().timestamp())
raise AirflowRescheduleException(dt_reschedule)
return super().execute(context)
In the dag, I have something as below. However, I notice when the mode is 'poke', which is default, the sensor will not work properly.
with DAG( schedule='0 10 * * 1-5', ... ) as dag:
task1 = MySensor(start_time=time(14,0), mode='poke')
task2 = MySensor(start_time=time(16,0), mode='reschedule')
... ...
From the log, i can see the following:
{taskinstance.py:1141} INFO - Rescheduling task, mark task as UP_FOR_RESCHEDULE
[5s later]
{local_task_job.py:102} INFO - Task exited with return code 0
[14s later]
{taskinstance.py:687} DEBUG - <TaskInstance: mydag.mytask execution_date [failed]> dependency 'Task Instance State' PASSED: False, Task in in the 'failed' state which is not a valid state for execution. The task must be cleared in order to be run.
{taskinstance.py:664} INFO - Dependencies not met for <TaskInstance ... [failed]> ...
Why rescheduling not working with mode='poke'? And when did the scheduler(?) flip the state of the taskinstance from "up_for_reschedule" to "failed"? Any better way to start the each task/sensor at different time? The sensor is an improved version of FileSensor, and checks a bunch of files or files with patterns. My current option is to force every task with mode='reschedule'
Airflow version 1.10.12