Embed a paginated report with RLS and CUSTOMDATA dataset shows error regarding CSDL.

I solved the puzzle. The thing is, if you want to use paginated reports, the dataset can't use RLS. Instead, to achieve RLS-like behavior, you should use the username attribute in the embedToken request and the built-in field 'User!ID' in the report builder expression.

Here's an example of an 'embedToken' request:

Endpoint: https://api.powerbi.com/v1.0/myorg/GenerateToken

{
	"datasets": [
    {
      "id": "dataset_with_no_rls_id",
      "xmlaPermissions": "ReadOnly"
    }
  ],
 "reports": [
 {
  "id": "report_connected_to_dataset_id"
 }
 ],
 "identities": [
 {
  "username": "constraint_value",
	"reports": [
		"report_connected_to_dataset_id"
	]
 }
 ]
}

Also, it's important to note that in order to use this approach, you must connect to the dataset using the XMLA endpoint. Otherwise, it won't work.