Ship with Walmart - First Class Labels - 1-3 oz items - Error

Does any other company use the Ship with Walmart (US Mail) First Class Label for 1-3 oz envelopes? We have been in the test program for 6 months and it stopped working this morning. The error is only occurring when you choose "ounces". Error: We are unable to retrieve shipping options due to a technical issue. Please try again shortly. If the issue persists, please try an alternative way to ship this order.