Hardware OS is CentOS Linux release 7.4.1708 (Core) running Samba 4.6.2-12.el7_4. On the Macintosh, there is an intermittent problem with being prompted for permission to rename a file or directory. But it won't accept any of the authorized user names and passwords. The permissions on the files and directories don't matter, even changing them with the chmod command to chmod 777.
The only way to "fix" this issue I have found, is to do a restart of the smb service on CentOS. Then the Mac problems with being prompted for permission no longer occurs.
I'd be happy to provide more extensive diagnostic information and more detailed logs to help trouble-shoot this. So far the bug has not been reproducible, but when it does occur which is frequent, restarting smb service does make the problem go away. We've been using Samba on CentOS for 11 years and have not had this specific issue until recently.