I discovered a different behavior with a syncrule run.
In the icingaweb2 interface it shows 30 objects to be created:
In the icingacli it shows 30 objects to be modified:
# icingacli director syncrule check --id 10
There are pending changes for this Sync Rule. You should trigger a new Sync Run.
Expected modifications: 0x create, 30x modify, 0x delete
The icingacli seems to be the correct one, because the objects are already there.