Synthesized answer
The provided passages do not contain enough information to answer the question about what questions remain unanswered. The given text only includes the title of the discussion and the page number [40]. Therefore, it is not possible to determine what questions were discussed or left unresolved in this specific excerpt.
Synthesized from the book passages below. Chat with the book on Feynman for follow-up.
From the book
Title: Discussion with Einstein on Epistemological Problems in Atomic Physics by Niels Bohr, Albert Einstein Pages: 40