Polybase and IRIS

Hi all, I am trying to use Polybase in SQL Server 2019 to access an external Cache/IRIS Database. I have followed the initial steps of enabling Polybase, creating a Database, DB scoped credential and then an External Data Source. These steps have not caused any issues and appear to be successful, I am using the same DSN we use for a Linked Server connection that works normally. I am running into an Error when trying to Create an External Table. The error is a generic Native Code 469 "Driver Not Capable". 

105082;Generic ODBC error: [Iris ODBC][State : HYC00][Native Code 469]
[C:\Program Files\Microsoft SQL Server\MSSQL15.MSSQLSERVER\MSSQL\Binn\Polybase\mpdwsvc.exe]
Driver not capable .
 

I am using the below syntax which I believe "should" be correct but have tried several variations. This was initially just a test to confirm Polybase was working and connected so I'm only pulling in one column so the complexity is pretty low.  I have seen at least one or two other posts where someone has stated they created a successful connection to Cache with Polybase but I've not seen anyone mention Iris specifically. Has anyone been able to get this working with IRIS? Any help would be appreciated.

 --Create External Table
   CREATE EXTERNAL TABLE [SYSTEM.billing_tx_master_table]
  ([SERVICE_CODE] [VARCHAR](20) NOT NULL)
  WITH (
  LOCATION='[SYSTEM.billing_tx_master_table]',
  DATA_SOURCE= AVATARLIVE
   )
  ;

Adam Doherty DBA