Apparently, the sale of El Greco's Saint Sebastian painting was suspended due to Romanian state's claim of ownership. Excerpts from the New York Times article:
Here, here and here are some of many heated FB discussions on this topic.
The painting, “Saint Sebastian,” depicting the body of its subject pierced by arrows, was created in the early 1600s and was estimated by Christie’s to fetch $7 million to $9 million at auction.
It now joins decades of legal battles waged by Romanian government officials who have said Michael removed cultural patrimony in the form of dozens of valuable paintings when he was forced to abdicate after World War II. The government regards the paintings as state property, not the former king’s personal possessions.
Christie’s said in its catalog that the work was transferred to Michael in 1947 “with the accord” of the Romanian government.
[...]
On Dec. 30, 1947, Michael left Romania via train with more than 30 family members and friends, issuing a decree that said the monarchy was an obstacle to the country’s future. While in exile, Michael and his wife, Princess Anne of Bourbon-Parma, lived mainly in Geneva.
The Romanian government eventually came to believe that six weeks before he abdicated, Michael removed 40 paintings from the country on a trip on the Orient Express to attend the wedding in Britain of his cousin Philip to Princess Elizabeth, the future queen. He deposited some at a Swiss bank and left others in Florence, the lawyers for the government maintained.
Michael sold “Saint Sebastian” in 1976, according to the Christie’s provenance, and the painting was acquired by its present unnamed owner in 2010 through the art dealers Giraud Pissarro Segalot.
By that time Romanian officials had already begun efforts to obtain works they said Michael had taken.
In 1985, the country’s Communist regime filed a lawsuit against the art dealers Wildenstein & Co. in Federal District Court in Manhattan seeking two El Greco paintings that it said were sold by Michael through the gallery. That case was dismissed when Romania did not comply with discovery orders from the court.
A successor government sued Michael in State Supreme Court in Manhattan in 1993, asking for the return of works by El Greco, Rembrandt, Caravaggio, Breughel and others. That suit, too, was dismissed.
Here, here and here are some of many heated FB discussions on this topic.