Purview Updating Entity, Assets column, description etc

Hello,

I am trying to update an entity in Azure Purview from Spark Notebook or through Postman. We have a default purview setup in Azure. However, through both ways I am able to fetch the data but I am unable to post anything. 

Following are the POST API calls that I have tried :

⁠https://%7B%7Bpurview_acc_name%7D%7D.catalog.purview.azure.com/api/atlas/v2/entity/

⁠https://%7B%7Bpurview_acc_name%7D%7D.catalog.purview.azure.com/api/atlas/v2/entity/bulk/

The error I receive always is : {"error":{"code":"Unauthenticated","message":"Token expired"}}
I also tried creating a new token and it hits the API correctly but just not able to authenticate the token.

There is already several discussions on it without any concrete solution : 
1. One solution was to check Content-Type, I tried out by selecting JSON as well(https://techcommunity.microsoft.com/t5/microsoft-purview/create-entity-api/m-p/3549161)
2. https://techcommunity.microsoft.com/t5/microsoft-purview/adding-custom-properties-to-an-entity-in-purview/m-p/2794655
3. https://techcommunity.microsoft.com/t5/microsoft-purview/api-to-azure-purview/m-p/3602951#M313

Documentation reference : 
https://learn.microsoft.com/en-us/rest/api/purview/catalogdataplane/entity/create-or-update?tabs=HTTP
https://learn.microsoft.com/en-us/rest/api/purview/catalogdataplane/entity/create-or-update-entities?tabs=HTTP


Can you please let me know, if there is a solution to this issue.

Thanks & Regards,
Karan