TS-RXL3B0 no Domain Users or Groups

[Sparky70]

Active Directory domain join works without issue yet the UI doesn't return anything for Domain Users or Domain Groups.  Navigating to Domain Users will prompt 'Loading Data..' but sits there for 5+ minutes and the session will eventually time out.

Config items confirmed:

• Current firmware is 1.72
• Computer account created with 'pre-Windows 2003 computer'
• Delegation set to 'Trust this computer for delegation to any service (Kerberos only)'
• DNS A & PTR records created
• Domain Controller GPO setting Network security: LAN Manager authentication level = Send LM & NTLM - use NTLMv2 session security if negotiated
• 'Get-SmbServerConfiguration command shows EnableSMB1Protocol = TRUE/li]
  

This use to work .... What am I missing?