We're working on a fix for this. As a workaround users can either test out roles using the Power BI Desktop or can continue to use the Power BI service by using their browser's back button to go back to the security page and test a different role.
You can track the latest resolution status by vistiing our support page at https://powerbi.microsoft.com/en-us/support/.
Yes i know this option,But suddenly today i could not test it ,The below screen does not apear to me,
If you have any report in Power BI service,Kindly test it ,Suddenly that feature is missng.
It seems it still works though no message showed up. A report has been submitted internally. I will post here if I get any updates. Sorry for the inconvenience.