Azure DB for PostgreSQL - changes to log_line_prefix parameter not implemented

Question

I have a General Purpose Single Server instance of Azure DB for PostgreSQL where I have installed the pgAudit plugin. I am trying to add more data to the pgAudit session auditing entries by following the instructions on Microsoft's page and PostgreSQL's page and I tried to set up log_line_prefix in the following configurations:

• t=%t c=%c a=%a u=%u d=%d r=%r% h=h% e=e c=%c
• %t,%c,%a,%u,%d,%r,%h,%e,%c
• %t%c%a%u%d%r%h%e%c

None of these have any effect on events collected. Here's the most of what an INSERT looks like:

{
  "LogicalServerName": "postgresql4moi",
  "SubscriptionId": "****",
  "ResourceGroup": "OLC_Research",
  "time": "2020-05-05T12:10:59Z",
  "resourceId": "***",
  "category": "PostgreSQLLogs",
  "operationName": "LogEvent",
  "properties": {
    "prefix": "t=2020-05-05 12:10:59 UTC c=5eb157c4.5c a=DBeaver 7.0.1 - SQLEditor <testingScript.sql> u=system d=postgres r=****.234(4344)h=he=e c=5eb157c4.5c",
    "message": "AUDIT: SESSION,6,1,WRITE,INSERT,,,\"INSERT INTO public.koko_table VALUES ('kokoMoko','kokoMoko')\",<none>",
    "detail": "",
    "errorLevel": "LOG",
    "domain": "postgres-11",
    "schemaName": "",
    "tableName": "",
    "columnName": "",
    "datatypeName": ""
  }
}

Is there something else I forgot to configure? I event restarted the database after each attempt to set the parameter.

Thanks in advance.