We're experiencing the same problem as in
MDEV-12837 on MariaDB-Galera 5.5.62 consisting of 3 nodes. As far as we know. the problem is fixed with MariaDB 10.1, 10.2, 10.3, but not with MariaDB-Galera 5.5. Can you also apply the patch to MariaDB-Galera 5.5? This is very critical to us. Please give us a reply.