So I've fixed the other issue of not being able to find the tiles api url. This might need updating in the documentation. It appears that for a users workspace you use: "https://api.powerbi.com/beta/myorg/dashboards/" + ds1.Id + "/tiles", however for groups you need to qualify with the specific group id: "https://api.powerbi.com/beta/myorg/groups/" + ds1.Id + "/dashboards/" + ds3.Id + "/tiles". This was a little confusing. But now I show all dashboards, reports and tiles.
