I've do some other test:
I've shutdown consumer (desynched), and I've do about 10000 random modify on producer, then I've set loglevel -1 on producer (due to find something wrong) and started consumer.
After a night, I've restarted the cluster again (producer and consumer) setting a relaxed loglevel on producer, but this time consumer was resynched!
Also the deleted DN ignored previously, are now in sych.
very strange.
Paolo