Python 3.6 IT tests: The Dataflow job appears to be stuck

 19:13:05 ======================================================================
19:13:05 ERROR: test_wordcount_fnapi_it (apache_beam.examples.wordcount_it_test.WordCountIT)
19:13:05 ----------------------------------------------------------------------
19:13:05 Traceback (most recent call last):
19:13:05   File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python3_Verify_PR/src/sdks/python/apache_beam/examples/wordcount_it_test.py", line 51, in test_wordcount_fnapi_it
19:13:05     self._run_wordcount_it(wordcount.run, experiment='beam_fn_api')
19:13:05   File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python3_Verify_PR/src/sdks/python/apache_beam/examples/wordcount_it_test.py", line 75, in _run_wordcount_it
19:13:05     run_wordcount(test_pipeline.get_full_options_as_args(**extra_opts))
19:13:05   File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python3_Verify_PR/src/sdks/python/apache_beam/examples/wordcount.py", line 114, in run
19:13:05     result = p.run()
19:13:05   File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python3_Verify_PR/src/sdks/python/apache_beam/pipeline.py", line 406, in run
19:13:05     self._options).run(False)
19:13:05   File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python3_Verify_PR/src/sdks/python/apache_beam/pipeline.py", line 419, in run
19:13:05     return self.runner.run_pipeline(self, self._options)
19:13:05   File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python3_Verify_PR/src/sdks/python/apache_beam/runners/dataflow/test_dataflow_runner.py", line 64, in run_pipeline
19:13:05     self.result.wait_until_finish(duration=wait_duration)
19:13:05   File "/home/jenkins/jenkins-slave/workspace/beam_PostCommit_Python3_Verify_PR/src/sdks/python/apache_beam/runners/dataflow/dataflow_runner.py", line 1240, in wait_until_finish
19:13:05     (self.state, getattr(self._runner, 'last_error_msg', None)), self)
19:13:05 apache_beam.runners.dataflow.dataflow_runner.DataflowRuntimeException: Dataflow pipeline failed. State: FAILED, Error:
19:13:05 Workflow failed. Causes: The Dataflow job appears to be stuck because no worker activity has been seen in the last 1h. You can get help with Cloud Dataflow at https://cloud.google.com/dataflow/support.