An invoice is set to Collections mode when the payment for it has been sent to us but we are yet to receive or process the transaction. This happens to an invoice when you send us payment via manual processes (eg.Cash Deposit, Wire Transfer, Credit Transfer etc) and the Billing Dept. is yet to approve the transaction. Usually, invoices in Collections would only take few hours before we approve them!
There is no further action required from you once an invoice is in Collections; we will process it or get back to you if otherwise. Be free to ask for support if you have further inquiries.