In 1939, the MAK bought a wrought-iron candelabrum from the Cistercian Abbey of Heiligenkreuz; in spring 1940, the museum also purchased, for a lump sum of 40,500 Reichsmarks, ten stained glass paintings from the Abbey’s priory Neukloster in Wiener Neustadt. After the end of World War II, the Abbey of Heiligenkreuz filed for cancelation of all sales of artworks and real estate from its possession under the NS regime on grounds that these had been forced by the regime with the threat of a closure of the Abbey. This was granted, with the Abbey returning the purchase prices paid. However, the Romanesque candelabrum was not restituted as it had been lost somewhere around the Sonnberg depot shelter in the final days of the war. The Abbey did not file for restitution of the ten glass paintings from Neukloster. Apparently, the entire transaction had fallen into oblivion after both the abbot of Heiligenkreuz and the prior of Neukloster had died in 1945. From 1998, the history of this purchase was traced back under the provenance research program.
In its meeting on 23 January 2009, the Art Restitution Advisory Board recommended the restitution of the ten glass paintings. Nine glass paintings were handed over to a representative of the heirs on 1 April 2009, the tenth glass painting was returned on 19 November 2009.