We are experiencing the same issue as reported here: https://community.powerbi.com/t5/Desktop/Users-with-multiple-security-roles-suddenly-can-t-see-data/m-p/2251588#M819234 The Power BI service i...
One more strange observation is that you were earlier able to select multiple role in Power BI service under 'Test as Role' option. Now you can select only 1 at a time
Also this is observed only in cases where the visuals are referring to any many-to-many relationship, in the model.
But that certainly is not a work-around as all of the many-to-many relationships can't be worked through or deactivated and work with a separate DAX written on the table for RLS.