Recently, I installed Minecraft Forge for mc 1.9.4. Later on, I tried giving me an item with a modified armor attribute stat, but it did not work, the item did not change.
This is the command I used:
/give @p minecraft:stick 1 0 {AttributeModifiers:[{Slot:"mainhand",AttributeName:"generic.armor",Name:"generic.armor",Amount:2,Operation:0,UUIDLeast:41580,UUIDMost:573197}]}
Then I tried the same command in Forge for mc 1.10.2, but it still did not work.
Finally I logged in with a mincraft vanilla v. 1.10.2 without Forge, and it worked correctly. Of course, before doing that I looked for some kind of explanation or bug report on internet, but did not find anything. So, I am writing this here because I guess it is a bug of Forge.
Summary:
And that is my report. I think you won't probably need my log, because it is easy to recreate this problem in minecraft and it does not crash the game, but here it goes: http://pastebin.com/SvfVmCdP