Update datasource of paginated reports

Hi guys, I'm currently working on a CI/CD pipeline to automate the deployment of pagniated reports. I tried to use this Update Data Sources In Group API call to update the datasource of my paginated report but keep hitting errors. 

Here is a snapshot of my powershell script. 

And this is the error I received:

This error message is very generic. It's hard for me to investigate based on this error message. 

I'm using a service principle to connect to the power bi service. tried to run some of the other API calls like get report datasource,etc  which work as expected. 

The service principle is the admin of the powerbi pipeline and the workspaces of the reports. 

Has anyone encountered the same error before? Any help will be much appreciated!