Hello, I have updated zone through the SOA interface, changing the "email" setting (it was incomplete since import). The on-disk zone was updated, but the serial was not incremented, so the secondaries did not fetch the change. This is probably a (minor) bug in 3.2.11
Did you use ISPConfig GUI or the API? If you use the API, then you must take care to update the serial in your API request.
Are you sure there are no errors in the zone file? In that case ISPConfig may create zone file with .err ending and the original zone file stays in place. I have never seen ISPConfig not updating the zone serial number.
There is and was no .err file and the zone had no change (other than mentioned) from previous version that was correctly generated and spread across secondaries. The datalog only has one record at 17:29, change at 17:28 went correctly and at 17:33 I forced soa to update (moving to "Zone rendering" tab and out)
I am out of ideas. Workaround would be to manually increase the serial by one, just edit the file. If you can make this strangeness happen reliably, file a bug report.
I'm not experiencing any bugs concerning dns in that version. I have a new multiserver install that started with that version. Dns works properly using the ISPConfig GUI and via API by LE. Multiple slaves (1 other ISPConfig server and other external servers) are updated accordingly.