users name not displayed

It doesn't display a name unless you turn the greeting on under Logout Options of your CB Login Module. The greeting will use the formatname field for its name display, which you need to ensure is set to display on profile or it won't display. By default the greeting is just "Hi, [formatname]" (e.g. Hi, Jimmm).

you cant edit article in frontend

Joomla article edit has nothing to do with CB.

You are not experiencing any form of bug. You just don't have things configured correctly.

The greeting doesn't output a linked name. We're adding ours manually using the "Logout Pre-text" and supplying "Hi, [cb:userfield field="formatname" reason="list" /]" so it links to the users profile. Your alternative is a language override to override the greeting language string and change it to the provided usage.

How to ensure formatname field is set to display on profile name display?

Ensure the field it self is set to display on profile in CB > Field Management (already should be unless you changed it) and is on a published and public profile tab (again, already should be unless you changed it). If you don't actually want it visible on their profile move it to a tab that's in a not shown on profile position.