Working with a customer, I found the below messages on the maxscale log what figures out to be a limitation of the Data Masking filter:
We need to be able to support a netmask with definition having numbers different of 255 or 0. Maybe, to support a CIDR definition will be good as well.
It's linked with the https://jira.mariadb.org/browse/MXS-1772. Can that support be implemented?
Thanks and cheers!