@Takis,
Thank you for your reply.
We just tested it again on server and we found that after adding a new user from Dashboard, it becomes available in Editor Lock's Page. Unfortunately, we are not able to reproduce your issue on our side and hence not able to give you the solution what needs to be done, however, if you are comfortable then we can check what is the issue your site. We are trying our best to help you.
If you don't have problem with this, then kindly contact us on info(at)wisdmlabs.com
Thanks,
WisdmLabs