We used to be able to test the RLS of multiple reports that shared the same dataset by going into the dataset's options --> Security --> Test as Role to view main report as a specific user. I could ...
bjkoning-bince ChristianMetzen , I created a new Power BI Idea to bring this feature back. Please vote here if you believe it is important: Bring back ability to test RLS for multiple reports on shared dataset in PBI Service