DNs with backslashes are not displayed by the ldap browser.
They can be searched for, and found. Once found, they will be displayed.
However, refresh, and they disappear again.
Example, create a user thus:
Now expand ou=people,dc=example,dc=com in the browser. The entry will not display.
Search for (uid=user.0\,foo) and it will be found (and displayed in the browser.
Refresh ou=people and it will vanish.