Users in same role can still see user names in same role even though they are blocked to message each other. Users who are blocked to another role should not be able to see users in that role in autosuggestion/autofill feature.
Thank you for your feedback. It seems there is a bug where if more than 1 is set as Max recipient, role block is not applied to the users. You can continue with this setup (Max recipient as 1) and i will fix this in the next release for other setup.