Hi Effamira,
The menu item used on the list page and the details form are two different ones with their possibly own security settings (AssetCopy and AssetCopyAction {listpage}).
Note that both are part of the security objects mentioned above. So, I guess the AssetCopyAction menu item has been changed within the privilege. Or someone changed the form control property of this menu item on the list page (changed NeededPermission to Manual). In that case, it is also not visible to users unless it has been overridden on the role as form control permission.