Hello.
1) block user (add to black list)
2) Disallow user to use privacy settings:
Settings > General > General > Enable Privacy.

Result: I can’t see area at Edit profile > Manage privacy > Manage Blocked Users. https://take.ms/zeQ6r — screen display how it should be. For example I can’t see this blocked users list on mobile.

Does it mean that user still in block list, but list is hidden? And it’s impossible to unblock user?

Thanks.