Check the 3rd party booking and see if there is a booking reference for
Virgin Australia (i.e. the carrier's reference).
If there is one, go to virtuallythere.com and fill in the blanks to bring up the e-ticket from the Sabre system. Whatever is on that e-ticket will stand as your booking, so if it says Business, it is Business (you should also be able to verify this by checking the fare code or basis, if available).
If the carrier reference is not for VA but another carrier (e.g. NZ), try using NZ's site to examine the booking. Try to obtain a copy of the fare rules for your booking, which may show the fare basis, and that should give away which class you are booked under.
I would harbour a guess that you're OK in Business, but no idea why the app is misreporting the information.