Hey there
My S II could not find any official updates to 4.1.2 - I'm currently on 4.0.4 and I've never received an update since, I got no idea why.
I've been trying to look for a solution and have tried quite a few things today, I just tried rooting my phone but that didn't solve the problem.

All my phones info is

Model: GT-I9100
Android version: 4.0.4
Baseband version: I9100NELP4
Kernel version 3.0.15-I9100XXLPQ-CL223505
Build: IMM76D.XWLPY

I am clueless too why I have this problem, hope some good people here can help me!

- Dennis