Same issue in OSP 16.0:

()[neutron@overcloud-controller-0 /]$ rpm -ql python3-networking-ovn-7.1.0-0.20200204065607.57ac389.el8ost.noarch | grep ovn_client.py
/usr/lib/python3.6/site-packages/networking_ovn/common/ovn_client.py
()[neutron@overcloud-controller-0 /]$ vi /usr/lib/python3.6/site-packages/networking_ovn/common/ovn_client.py
()[neutron@overcloud-controller-0 /]$ grep 'self._nb_idl.lsp_get_up(floatingip['port_id']).execut' /usr/lib/python3.6/site-packages/networking_ovn/common/ovn_client.py -C10
()[neutron@overcloud-controller-0 /]$ grep 'self._nb_idl.lsp_get_up' /usr/lib/python3.6/site-packages/networking_ovn/common/ovn_client.py -C10
            ovn_const.OVN_ROUTER_NAME_EXT_ID_KEY: gw_lrouter_name}
        columns = {'type': 'dnat_and_snat',
                   'logical_ip': floatingip['fixed_ip_address'],
                   'external_ip': floatingip['floating_ip_address']}

        if config.is_ovn_distributed_floating_ip():
            port = self._plugin.get_port(
                context, fip_db['floating_port_id'])
            columns['logical_port'] = floatingip['port_id']
            ext_ids[ovn_const.OVN_FIP_EXT_MAC_KEY] = port['mac_address']
            if self._nb_idl.lsp_get_up(floatingip['port_id']).execute():
                port_net = self._plugin.get_network(context,
                                                    port['network_id'])
                if port_net.get(pnet.NETWORK_TYPE) != const.TYPE_VLAN:
                    columns['external_mac'] = port['mac_address']

        # TODO(dalvarez): remove this check once the minimum OVS required
        # version contains the column (when OVS 2.8.2 is released).
        if self._nb_idl.is_col_present('NAT', 'external_ids'):
            columns['external_ids'] = ext_ids

I originally wanted to fix networking-ovn to make traffic centralized even after the reboot [1] but I think this is actually a problem in configuration that will be fixed by bug 1766930.

Andreas, are you fine closing this BZ as a dup of 1766930 ?

[1] https://github.com/cubeek/neutron/commit/7393cccf12d4d48f0391522e8d1e2959f7d0604e

Sorry for the long delay. https://bugzilla.redhat.com/show_bug.cgi?id=1789836 is closed. Shouldn't this bug be fixed then, too?

Closing EOL, OSP 16.0 has been retired as of Oct 27, 2020