Hi,
I'm playing this game more than 2 years. I saw many good things and many bad things.
After update 14.0 I noticed that opponents in AW sometimes just breaking my block and attacking me, although I'm blocking. At first I thought maybe it Assassin mastery or specific buff, but this war I saw the video that I recorded and made is super slow motion to show the issue (07:28):
https://youtu.be/FHZdN2zt8E0?t=7m28s
This issue happened me a lot and only in Alliance War. I hope this video will help you to identify the root of the issue.