GCPのbqコマンドでエラー発生で困っています

Question

GCPの勉強を始めたばかりの者です。（クラウドの知識は全くありません。）

bq mkコマンドでエラーが発生します。
SDKを再インストールしてみましたが、現象変わりませんでした。
解決策をご教示いただけないでしょうか？

[環境]
Windows10
Google Cloud SDK 288.0.0
bq 2.0.56
core 2020.04.03
Python 2.7.13

[問題]
C:\WINDOWS\system32>bq mk sample_dataset1
You have encountered a bug in the BigQuery CLI. Please file a bug report in our
public issue tracker:
https://issuetracker.google.com/issues/new?component=187149&template=0
Please include a brief description of the steps that led to this issue, as well
as any rows that can be made public from the following information:

== Platform ==
CPython:2.7.13:Windows-10-10.0.18362
== bq version ==
2.0.56
== Command line ==
['C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform/bq\bq.py', '--application_default_credential_file', 'C:\Users[path]\AppData\Roaming\gcloud\legacy_credentials[mailaddress]\adc.json', '--credential_file', 'C:\Users[path]\AppData\Roaming\gcloud\legacy_credentials[mailaddress]\singlestore_bq.json', 'mk', 'sample_dataset1']
== UTC timestamp ==
2020-04-08 08:23:09
== Error trace ==
Traceback (most recent call last):
File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform/bq\bq.py", line 1121, in RunSafely
return_value = self.RunWithArgs(*args, **kwds)
File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform/bq\bq.py", line 4049, in RunWithArgs
if client.DatasetExists(reference):
File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\bq\bigquery_client.py", line 3748, in DatasetExists
self.apiclient.datasets().get(**dict(reference)).execute()
File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\bq\bigquery_client.py", line 840, in execute
return super(BigqueryHttp, self).execute(**kwds)
File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform/bq\third_party\googleapiclient_helpers.py", line 131, in positional_wrapper
return wrapped(*args, **kwargs)
File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform/bq\third_party\googleapiclient\http.py", line 857, in execute
raise HttpError(resp, content, uri=self.uri)
File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform/bq\third_party\googleapiclient_helpers.py", line 131, in positional_wrapper
return wrapped(*args, **kwargs)
File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform/bq\third_party\googleapiclient\errors.py", line 43, in init
content = six.ensure_binary(content)
AttributeError: 'module' object has no attribute 'ensure_binary'

Unexpected exception in mk operation: You have encountered a bug in the BigQuery
CLI. Please file a bug report in our
public issue tracker:
https://issuetracker.google.com/issues/new?component=187149&template=0
Please include a brief description of the steps that led to this issue, as well
as any rows that can be made public from the following information: