Unable to generate PDF using REST API and Embed Capacity

[simbexpb]

I have followed all the steps in setting up service principal account and the PDF content is not coming as expected.
I get the following error and stuck, please help:

Cannot load model 
Couldn't load the model schema associated with this report. Make sure you have a connection to the server, and try again.
Please check the technical details for more information. If you contact support, please provide these details

What I have done so far:
1. Created PowerBI workspace, datasets, reports - all working from the UI
2. Created power BI embedded capcacity through Azure

3. Registered a new app with service principal account

4. Logged via POSTMAN https://login.microsoftonline.com/{TenantID}/oauth2/v2.0/token
5. Generated PDF using https://api.powerbi.com/v1.0/myorg/groups/{groupID}/reports/{reportID}/ExportTo

Report gets generated but PDF is empty with error message: 
Cannot load model 
Couldn't load the model schema associated with this report. Make sure you have a connection to the server, and try again.
Please check the technical details for more information. If you contact support, please provide these details

[v-xiaoyan-msft]

Hi @simbexpb ,

Is the data source you are using SSAS?

Any RLS settings apply on this dataset? Please aslo check if you maps to correct data source, And if the account you used in credential have access to the database you used in dataset?

Best Regards,
Community Support Team _ Caitlyn