After a better inspection, I found the following errors while doing the initial LDAP synchronization:
I, [2024-07-03T12:01:55.494663#505-149100] INFO -- : Skipping. No Role assignment found for login 'bvalmori'
I, [2024-07-03T12:01:55.498363#505-149100] INFO -- : Skipping. No Role assignment found for login 'francr'
I, [2024-07-03T12:01:55.501636#505-149100] INFO -- : Skipping. No Role assignment found for login 'dfish'
...
I, [2024-07-03T12:01:55.514668#505-149100] INFO -- : 2024-07-03T12:01:55+0200: [Worker(host:zammad-test pid:505)] Job AsyncImportJob [61989e27-8a4d-469b-b792-a8a7386245b4] from DelayedJob(default) with arguments: [{"_aj_globalid"=>"gid://zammad/ImportJob/11"}] (id=71) (queue=default) COMPLETED after 321.7847
Therefore, I suspect that even if the dialog at the end of the synchronization reports that 29 users and 29 groups have been created, these are somehow in a bad state and hence not visible.
Now, I double checked and the configuration for the LDAP integration selects the correct LDAP group (where the 29 users are) and assigns the agent profile.
Also, the UI does not show any “Recent Log” and does not mention any skipped user (skipped: 0).