When an invoice is not fully reconciled the error Cannot Proceed, Transaction not fully reconciled will appear when the user attempts to authorise or post the transaction. The reason is because the Supplier setting 'Reconciliation Required' is set to Yes.
From the Toolbar click on Purchase Ledger.
Followed by on Suppliers.
Click on the Suppliers tab then click on the POP sub-tab.
Reconciliation Required set to Optional.
Click Apply to Save changes.
This allows the user to progress with the authorisation and post the transaction.