"Convoy got stuck holding the bag after their partner carriers went under, having already paid them for their service, but still waiting for payment from the shipper."

This doesn't make any sense. What you're describing is normal course of business. Shipper pay terms are usually longer than when the carrier get's paid from broker. "Carrier's went under", doesn't make any difference. If the shipper doesn't pay, than that's a problem. But to say paying carriers that "went under" contributed to Convoy going out of business just isn't accurate.