I'm trying the new composite model feature released in the Dec 2020 update but keep getting "An error occurred while loading the model. Verify that the connection information is correct and that you have permissions to access the data source." error. I'm live connected to a PBI dataset and I'm trying to add connection to another dataset. Both datasets are in a Premium capacity node and are being fed data from an on-prem SQL server via a data gateway. Any suggestions on how to resolve this?