samba - May 2018 - ADSI Edit enumerates all domain computers but ADUC shows nothing

An old, standalone Samba 4.1 DC is in the process of being replaced by a
new Samba 4.7 DC. Although Windows ADSI Edit enumerates all of the
computers in the domain, Windows ADUC shows nothing, not even a single 
domain controller. DNS is populated correctly. GPO refuses to accept
scopes that include computer names.
    What's the best way to correct this situation? Thank you in advance.

73,

-- 
Don Kuenz, KB7RPU

There was a young lady named Bright
Whose speed was far faster than light;
She set out one day
In a relative way        
And returned on the previous night.