Maxscale shows slaves as Slave of External Server, Running

We have this setup :

1 master + 3 slaves

I want to configure Maxscale with query splitting :

[db1]
type=server
address=10.0.1.7
port=3306
protocol=MariaDBBackend

[db2]
type=server
address=10.0.1.8
port=3306
protocol=MariaDBBackend

[db3]
type=server
address=10.0.1.9
port=3306
protocol=MariaDBBackend

[db4]
type=server
address=10.0.1.10
port=3306
protocol=MariaDBBackend

[MariaDB-Monitor]
type=monitor
module=mariadbmon
servers=db1,db2,db3,db4
user=max
password=maxpass
monitor_interval=2000
detect_replication_lag=true

[Read-Write-Service]
type=service
router=readwritesplit
servers=db1,db2,db3,db4
user=max
password=maxpass

The servers are replicating fine, but when I execute a 'maxadmin list servers' the following output :

Server             | Address         | Port  | Connections | Status
-------------------+-----------------+-------+-------------+--------------------
db1                | 10.0.1.7        |  3306 |           0 | Master, Running
db2                | 10.0.1.8        |  3306 |           0 | Slave of External Server, Running
db3               | 10.0.1.9       |  3306 |           0 | Slave of External Server, Running
db4               | 10.0.1.10       |  3306 |           0 | Slave of External Server, Running
-------------------+-----------------+-------+-------------+--------------------

All slaves are marked as "Slave of External Server, Running". When I use "ignore_external_masters=true" it simply will see the slaves as running.

Servers : Server version: 10.0.32-MariaDB-1trusty mariadb.org binary distribution maxScale Version 2.3.2

The maxscale user has all appropriate rights.

Any idea? I can provide more info if needed.