There is an active issue saying: "Reports authored with latest PBI Desktop features enabled are automatically upgraded to v3 model schema. The delay in upgrading Analytical Workspaces leaves the F&O service dependent on solutions authored using v1 modeling tools". Right now we are restricted to use Sept 2020 version to author compatible reports.

The december 2020 was the greatest Power BI update in a long time it would be very valuable for customers to use all the new features on their D365 data. Please consider this on the product backlog! Thanks!