Is there a method via the API to convert an LDAP user to a local user, or Local user to LDAP? I see the key fields of LdapCcmPkid, LdapType, and LdapCcmUserId. Setting LdapType to 0 or 3 will move the user back and forth but not completely. For example if I manually set the user to LdapType 0, then look to at the LDAP Import list the user doesn't show up. I'm thinking this is because of the other fields which still remain behind, unless done through the GUI then they disappear. But I haven't found a method to remove these fields or even make them blank. Any REST API 'PUT ' for these fields results in an unsuccessful REST response.
Which CUCN release are you on? I've been fighting with this myself as you may have seen from my previous threads. I then filed a case, and it appears this is supposed to work, but is broken in 10.5.2 - I was told I could roll back (but can't as this breaks AD integration if samaccountname changes), or upgrade the 11.5 when it's done.
There's a defect you can track: CSCuu97867. I'm waiting for an ES on 10.5.2 to get this functionality as I need to convert users. Basically, you can change the LdapType just fine, but the API doesn't make the corresponding changes to LdapCcmUserId and LdapCcmPkid (unlike the GUI where it does just that to convert a user).
As for showing up in the import - I suspect once this is fixed, you'd still have to wait for an AD sync cycle before things are done.