I've been farming the anniversary bosses on a few characters and have gotten a few warforged upgrades. AMR isn't reading them as warforged, only as ilevel 900 items.
Example: My character Tormyn on Aerie Peak (US) has boots and a ring that are both warforged, but AMR shows them as 900. The armory shows both of them at the correct 915. My neck from Kazzak is showing the socket that it was upgraded with, so that seems to be working correctly. I haven't seen any tertiary stats on any of that gear so I'm unsure if that's an issue as well.
Probably related: I had a 915 belt on another character that I got from Black Temple timewalking that used to read as 915, but more recently had the same issue with showing only as a 900 item. I no longer have that belt though.