I tried another game as Austria Hungry. This time I focused most of my army on the eastern front, and pretty much worked alone at beating Russia.
I made sure I claimed what I wanted, namely the Ukraine region. However when peace fired Germany still took most of Russia, including Ukraine (minus Odessa, which I got).
This was pretty frustrating. Is there some event that supersedes any claim? It looks like the Soviet revolution happens...then a day goes by and Germany gets most of west Russia.
I tried peacing out on my own but it wasn't accepted. I had taken Moscow, St. Petersburg and obviously many other VPs.