Hi
We had the same issue and sent it through and it was accepted. We did a little searching on the ATO and found this information which may help to explain the error - In your STP report, salary sacrifice components appear as positive amounts regardless of the salary packaging method you use. It's important to understand how your product manages salary sacrifice because some products may require you to enter negative amounts into your payroll so that calculations can be completed correctly. It is also mentioned in the ATO Webinar https://tv.ato.gov.au/ato-tv/media?v=bi9or7odm11xjw at about 1:05 min in.
MYOB could put a tick box (like they do for reduction of annual leave etc) that could automatically reduce gross wages. This would make the deduction a positive.
