Hey gillhalloway,
There are a few things to check; If this is your first filing on QuickBooks then the transaction must be dated on or after the start date of the open per
If you have the VAT accounting scheme set to Cash within the Taxes settings then only sales invoices which have been marked as paid will post to the return.
You should also check that the transaction is dated within the date range of the open return, or this may be showing as an exception.
Thanks
