Have XTRACE=10 set in the xcom.glb file but no .TRA files appear to be getting created.
The xcom.glb file had EXPIRATION_TIME=60 (seconds) compared to the default value of 6000.
The XCOM.GLB parameter EXPIRATION_TIME refers to:
The maximum time, in seconds, that a transaction is held in the transfer queue after it is executed. When the maximum time is reached, all references to the transaction are removed from the queue, including trace files and temporary files.
So a value of 60 seconds results in the .TRA files being removed after 1 minute and thus they were getting missed.
The xcom.log also contains the corresponding message:
XCOMN0017I Transfer expired and was removed from queue.
Increase the EXPIRATION_TIME back to the default value of 6000 or higher if required during testing.