Yes, we had one line on the forms that was Calibri. Changed that to Arial and saved. It now works like it has for the previous 10 years and 50,000 invoices. Whether is a font issue or as MYOB mentioned above, just any change fixes it - who knows.
MYOB, who do we bill for all the wasted hours?
EDIT: for us in was absolutely due to using Calibri. Any forms that were all Arial continued to work. Any forms with any Calibri (which were many) didn't. Changed them to Arial and all forms now work (like they always had). For us it was definitely font. Changing anything else and re-saving had no change for us. The font change away from Calibri did. So MYOB, what have you got against Calibri all of a sudden?