FreeIPA ldap sync

Dears

I installed the latest axigen (10.4.2) using their vmware ova, based on ubuntu 22.04.
Server is up and running but I struggle to get ldap working with freeipa (more or less the better of openldap).

The log says:
2023-01-10 16:00:35 +0100 08 max1 USERDB:00000002: LDAP bind succesful for hosturl=‘ipa-ca.backbone.admin:636’
2023-01-10 16:00:35 +0100 08 max1 USERDB:00000002: Connected to server ldaps://ipa-ca.backbone.admin:636 from domain backbone.admin
2023-01-10 16:00:35 +0100 02 max1 USERDB:00000002: Failed OpenLdap search basedn(dc=backbone,dc=admin), filter((&(objectClass=inetOrgPerson))), error(Content Sync Refresh Required) on domain backbone.admin

Here the config:

The attributes for the ldap connector: FreeIPA:
accountBaseDN = “dc=backbone,dc=admin”
axigenHostField = “”
bindDN = “uid=axigen,cn=sysaccounts,cn=etc,dc=backbone,dc=admin”
bindPass = “…”
clusteredSetup = no
customSchemaFile = “freeipa_schema.cfg”
groupBaseDN = “”
ignoreLDAPDeletes = yes
ldapURI1 = “ldaps://ipa-ca.backbone.admin:636”
ldapURI2 = “”
ldapURI3 = “”
ldapURI4 = “”
ldapURI5 = “”
name = “FreeIPA”
pollingInterval = 10
replicaId = 0
searchDomainAliases = no
serverType = OpenLDAP
synchronizationConflictResolution = ldapWins
synchronizationDirection = ldapToAxigen
timeout = 4
transientErrorRetryInterval = 5
useCustomSchema = no

The attributes for the domain: backbone.admin:
appenderHtml = “”
appenderText = “”
assignedIP = 0.0.0.0
brandingName = “”
catchAllAccountName = “(none)”
catchAllFolderName = “(none)”
catchAllType = disabled
createUsersFromLdap = no
customerReference = “”
defaultLanguage = “en”
defaultTimeZone = “GMT+1”
disposableMetadataQuotaThreshold = 25
enableAppender = no
enableGravatar = yes
enableLDAPSync = yes
enablePushNotificationGenerator = no
ldapSyncConnectorName = “FreeIPA”
name = “backbone.admin”
publishRcptContacts = yes
services = (smtpIncoming smtpOutgoing pop3 imap webmail)
sharedFoldersNamespace = “Other users’ folders”
showWebmailLogin = no

On the same host running an ldapsearch with the same parameters from the terminal successfully responds:
ldapsearch -x -H ldaps://ipa-ca.backbone.admin:636 -b “dc=backbone,dc=admin” “(&(objectClass=inetOrgPerson))”

numResponses: 47

numEntries: 46

Any idea what might be missing or why the ldapsearch in axigen fails?
Any help and hints are highly appreciated!

Thank you!
Fritz