Not exactly the same issue, but I recently had a Buyer who was not able to see all the details on a Combined Postage invoice.  When I looked at it, all appeared correct.  By memory, it was 10 or 11 items and Registered Post, but she kept getting only one item appearing with standard post.  In the end I sent a Request to Pay via PayPal and then marked the order as Paid - that way no-one lost out on Fees and I didn't lose the sale, which was about to happen.

I have had to do this twice recently . . . . . . glitch maybe . . . . . .  ?