Hi,
Based on my research , the pwdssp.dll is necessary for the simple ldap research, just add the registry back .
Similar cases for your reference:
https://social.technet.microsoft.com/Forums/lync/en-US/40755056-45c8-480f-9337-fbe2f18c8c15/ldap-simple-bind-failing?forum=winserverDS
https://hi.service-now.com/kb_view.do?sysparm_article=KB0754219(Please note: The given technical support contact information belongs to a third party and may vary without notice. Microsoft does not guarantee the information accuracy.)
Best Regards,