It will be interesting to see if this story unfolds publicaly, because the original sales seem odd. The laws of 33 are significant, it's the year Jews lost most of their rights, including the right to deal in art. Don't know about 32, the year Hitler came to power, but 29 would have been a different issue, as would Amsterdam pre invasion. And catalogs (primary source material in these cases) list Mauthner as the owner in 1928-1939 and 1970. When Liz bought the painting, looted art was a wink and nod issue in the art world, like collecting on an insurance policy without a death certificate from Auschwitz.
Clearly Liz wants a clear title, to sell it or pass it on.
If Wolf left for Argentina in 1933 did he have the painting with him? When did he buy it? From whom? These questions have answers. The Mauthners seem less than enthusiastic about answering them.