Or couldn't recover the loot for another reason. The Reich and the USSR made a joint operation in the dismemberment of Poland.
I’m reading the autobiography of Geddy Lee (singer, bassist for the group RUSH). One entire chapter is about his mom as a Jewish child living in Poland and going to the camps. He said as the Germans got more power (before the invasion) the anti-semitism from the Poles increased, and of course was terrible after the Germans invaded Poland. With what were once friends and neighbors singling them out as “JUDES”.
After the war his mom’s family returned to Poland to their home but were chased out, with the Poles keeping their personal belongings left in the home.
She returned 50 years later, and some of the Poles would still shout at her and call her names!
All that said, my first thought was a stash buried by a Jewish family before they were rounded up and sent to the camps.
maybe in the very beginning, but I never heard of any ussr joint ops with germany after germany invaded Russia!