Hi Ant,
It looks to me like: com.arjuna.ats.internal.jta.recovery.arjunacore.XARecoveryModule::addXAResourceRecoveryHelper(XAResourceRecoveryHelper) isn't being called for your adapter. You could try a breakpoint in there to confirm that, depending on the version of IJ you are using the source for JBoss Transactions is available https://github.com/jbosstm/narayana/ or http://anonsvn.jboss.org/repos/labs/labs/jbosstm/tags/.
IronJacamar will call addXAResourceRecoveryHelper for an appropriately defined adapter so I presume there is an issue in your adapter?
Thanks,
Tom