It is pretty well known that Nazis discouraged US companies from having local representatives who were Jews. I imagine it did not happen all at once and the way foreign Jews were treated was quite different prior to WW2 than German Jews were. Interestingly, Irving Thalberg needed surgery and I guess Germany was so superior to the USA medically prior to WW2 (as it was in many other areas) that he went there and was successfully treated even though friends were worried about this.
I doubt that there were many Jews in the USA diplomatic corps in those days but we do know that Molotov replaced a Jewish diplomat and that in fact there were many Jews in the Soviet corps. So in the early days of USSR Nazi dealings, did Jews actually visit Nazi Germany or have other dealings with Germany?