Regret to hear that. 
Does the lip sync issue starts from chapter 15 until the end or just a few portions lang? 
Yes, there's an audio delay from chapter 15 until the end.
But the good news is that the delay is probably small enough to be unnoticeable to most people.
Another positive note is that the only portions where the delay is obvious to me are:
(a) The start of chapter 15 (from the coffee machine's closing lid to Upham translating the Edith Piaf song); and
(b) The ending (at the cemetery).
In between those parts, the delay is not so noticeable to me.
Try googling
saving private ryan sync and you'll get hits from avsforum (US), avforums (UK), and blu-ray.com.
