Embed Paginated Report Power BI Dataset - App Owns Data (Embed for Customer)

Hi all

I am using Power BI Embedded SKU A1, Gen 2.  I have created a workspace, Azure App, given the app all API permission to the PBI Service, addedd the service principal into a security group and givent that security group admin access tot he workspace that has the embedded capacity.  (Understand that the privelages right now are above required, but wanted to ensure that was not the problem)

I am using Postman to genearate access tokens, embed tokens and retrieve the embedded url.  I am then using the Power BI Playground to test out my report.

For a normal PBI report, I can get this working fine and even down to RLS, works great.

However for a Paginated report, I can get it working under 2 conditions, a report with no data (not too useful!) and a report with data entered directly into the report (also not that useful!).  These render correct in the playground.

However once I use a PBI Dataset (import or direct query), the report does not render and I receive the error

I have tried many way to get this to work but to no avail and I am note sure what I am missing.  If I follow the MSFT instructions for the HTTP payload from the following location

https://docs.microsoft.com/en-us/rest/api/power-bi/embed-token/generate-token#example-of-generating-an-embed-token-for-a-paginated-report-which-has-a-power-bi-dataset-as-a-datasource.-the-id-of-the-dataset-must-be-specified-in-the-request.-the-report-and-dataset-can-each-have-its-own-identity

I have tested multiple ways of creating the payload and end up with the same error message each time.

Can someone please assist and advise on what I am missing?

Thanks