NAV 2018 Lanham EShip Paperless Commercial Invoice Limit

We’re on NAV 2018 using Lanham EShip for UPS packages. We implemented the Paperless Invoice and it is mostly working. In UPSLink, the checkbox is on the FastTab Contract Services. On the UPS Option Page Card for UPS Standard, on FastTab International for setting Commercial Invoice, we selected Paperless Invoice.

Occasionally, NAV prints only a small portion of the bar code. If we scan the bar code, there is an alert, “Shipment data exceeds bar code capacity. Shipment must be keyed.”

Does anyone know what the limit is (character count, rows of SKUs, something else)?

Many thanks!