Hello Paul,
I did a little testing here and it looks like we CR is trying to convert the chr(9) to a barcode, unsuccessfully, and displays nothing.
However I was able to come up with a workaround by creating 2 formulas,
formula 1
barcodeC39(job.job-id)
formula 2
barcodeC39(job.sub-job-id)
Add both to the report and change to barcode. Insert a text object and then drag both formula fields into the text object. You can then edit the text object to place a tab in between the 2 formulas.
Regards,
Graham