"Some submissions during 15-20 May have not been reported correctly to the ATO. Click Send update event to report them."

If anyone's wondering, I ended up logging into the ATO Online Services and comparing the list of reports submitted there to the list in the MYOB portal. They were all there so I've assumed I don't need to take any action. Still can't get anyone to tell me if the 'send update event' still creates a $0 payslip for every employee that'll end up in the 'to be emailed' window.