From 1907, Mayer-Mahr was one of the judges of the Ibach competition for young artists at the Stern Conservatory. He founded the Mayer-Mahr Foundation to support his students, to which he contributed the considerable donation he received on his 60th birthday.
After the seizure of power by Hitler, Mayer-Mahr lost his seat in the senate of the Academy of Arts, Berlin in 1933 because of his Jewish origins. In 1935 he was expelled from the Reichsmusikkammer. In 1936 he was finally banned from working in the music business. However, he was still allowed to teach foreigners and members of the Jüdischer Kulturbund. In 1937 he left the Klindworth-Scharwenka Conservatory. In 1937 he appeared at an event of the Kulturbund Deutscher Juden with the cellist Leo Rostal of the local orchestra and the concertmaster Wladislaw Waghalter and, again in 1938, for the Jüdische Winterhilfe. In 1938 he taught the Spanish conservatory student Ursula Reig free of charge, which brought him a lawsuit from the local musicians for violation of the professional ban. The proceedings initially resulted in fines, but were eventually dropped.
In 1940, Mayer-Mahr obtained the exit permit for himself and his second wife Paula née Sternberg. They first went to Norway, lived briefly in Vestre Aker and fled from occupied Norway to Sweden, where he taught again. His son Robert did not succeed in escaping; he was deported from the Drancy internment camp to the KZ Auschwitz in 1942 and has been missing since then.
In Sweden were published Mayer-Mahr's Kåserier kring pianot[3] in 1943 and in 1947 Ernste und heitere Erlebnisse rund um das Klavier.[4]
