Datasets details in the metadata API

Hi, we are using the metadata scan APIs to try to get reports/datasets info in a worksapce.
We have requested all info 

https://api.powerbi.com/v1.0/myorg/admin/workspaces/getInfo?lineage=True&  datasourceDetails=true&datasetSchema=true&datasetExpressions=true&getArtifactUsers=true

We also enabled the following 3 permission in power bi 
The thing is that, for some of the datasets, we see detailed tables info, and the expressions. But for others, we just don't see anything.
Anyone knows why is that?