This list is terribly incomplete. It's missing all of the artifacts stolen by the Soviet Army during WWII, and still not accounted for.

The USSR systematically stole from all the areas they occupied. They stole the indexes and inventories, so it's not known what was taken.

Entire libraries and museums just vanished.

The Soviets implied they were destroyed in the war, but there is strong evidence the Soviet system of looting preserved much. In the early 1990s, some treasures started to leak out.

Wikipeia is good at some things, and terrible at others. Compiling a list of "missing treasures" is far beyond it's competency.