Resolve this error by following the steps below

Select Lists > Relationships > Vendors > Search
On the next page, search for the vendor from Plate IQ that generated the flagged invoice.
At the bottom of the vendor page, select Edit to add a subsidiary.
From the dropdown, add the correct subsidiary. Click Save when finished.
Navigate back to Plate IQ. Click Resolve Flag.
Click Export and the invoice will flow to NetSuite properly.
Note: You may need to refresh your NetSuite to see the invoice populate