Orders not syncing correctly

I’ve been using WPC Composite Products for a couple months now and it mostly works great. However, there has been two times that the composite products did not sync on the customer’s order. Only the base product shows up. One of the times, the customer didn’t even pay for shipping (I have shipping set up for composite products only). They did choose their required composite products with the base product, so I don’t know why this happened. Is this a bug, or is there a way to fix this?