I have Steam version of FNV (disk from 1C, Steam version) plus Dead Money DLC (downloaded from Steam). And my version still also 1.2.0.352
So, I have the same problem with update and the same question to Bethesda's support team.
I think as long as we have such problems with 1C, a lot of PC gamers in Russia don't purchase license disks from this company and usually it's simple enough to find another way to get one

For example, not so long ago, I had a huge problem to update Fallout 3 because I bought license disk from 1C...