Avrorouter generates empty avro files in CDC

Hello,
I have enabled the binlog service and the avrorouter in order to have CDC Json logs on Maxscale, the binlog service works fine, generating the binlog files correctly.
The avrorouter, instead, produces a well-constructed avsc file but the avro file remains empty (0 bytes size).

The main error that I can see are:

2018-07-04 15:54:44 error : [avrorouter] Avro error: Cannot read 4 bytes from file
2018-07-04 15:54:44 error : [avrorouter] Failed to open new Avro file for writing.
2018-07-04 15:54:44 error : Failed to read file magic marker from '/var/lib/maxscale/test.t6.000001.avro'