Invoiced doesn't necessarily mean they meet they revenue...

Invoiced doesn't necessarily mean they meet they revenue recognition criteria and if they don't and invoice the customer then they would defer on the balance sheet as a liability. Revenue should be recognised when control of the goods pass to the buyer, this will depend on the agreed shipping terms. If buyer is responsible for shipping, then once goods are on ship they can recognise revenue. This means if shipments can sometimes take up to 90 days then revenue might not be recognised for up to 3 months subsequent to invoice date. My understanding is that ZNOs agreements (not sure if all or just some) would be for up front payment which is why they would invoice before shipping. So they might have received the cash from the $11m in say April/May but revenue would have been recognised as they shipped so maybe across at least 2-3 quarters especially when global shipping had slowed right down.