Azure Blockchain Workbench container registry throwing Unauthorized

Hi Team,

We have deployed a brand new version of the Azure Blockchain workbench on our Azure Subscription.
On the day of provisioning the services, everything was working fine and the API as well as the Workbench dashboard was working fine.
But after 3-4 days, when visiting back the workbench, the below error is what we encounter -

when looking into the docker logs, below is what I see -

`2020-09-15T00:02:39.011Z ERROR - Image pull failed: Verify docker image configuration and credentials (if using private repository)
2020-09-15T00:02:39.024Z INFO - Stopping site pocblkchainsept-2gtmxa-api because it failed during startup.
2020-09-15T00:07:38.419Z INFO - Pulling image from Docker hub: blockchainworkbenchprod.azurecr.io/appbuilder.api:1.8.1
2020-09-15T00:07:38.990Z ERROR - DockerApiException: Docker API responded with status code=InternalServerError, response={"message":"Get https://blockchainworkbenchprod.azurecr.io/v2/appbuilder.api/manifests/1.8.1: unauthorized: authentication required, visit https://aka.ms/acr/authorization for more information."}`

The similar issue was reported in the link - https://social.msdn.microsoft.com/Forums/en-US/5233adb9-efe8-4f23-94d1-1b6706007beb/azure-blockchain-workbench-container-registry?forum=opensourcedevwithazure but there are no resolutions / workarounds.

Kindly provide inputs.