Row Level Security - Member changes not saving

We had to implement the workaround by getting our site admin to remove premium capacity from workspace and then set it back as we couldn't wait for the Feb fix, which doesn't seem to have worked.

Latest update on the issue can be found at https://powerbi.microsoft.com/en-us/support/ 

It now says March for resolution:

Power BI customers with premium capacities using Row Level Security may experience issues while adding external guest users (AAD B2B) to roles with the message, "The Role could not be updated. Please try again later". As a workaround, users can move their workspace to Shared, add the external guest user, then move it back to the capacity. Engineers have identified the issue and a fix is expected to be deployed by end-of-day 03/07/2021