What was the specific problem Das Ganu encountered with his commentary on the Ishavasya Upanishad, and what guidance did Sai Baba provide in Chapter 20?

In Chapter 20, we learn about the spiritual and intellectual challenge faced by Das Ganu. He had started a project to create a commentary on the Ishavasya Upanishad to explain its profound meanings in simple language. The problem, as Chapter 20 clarifies, was that while he could perform a literal, word-for-word translation, he failed to grasp the "internal secret" or the deeper essence of the scripture, leaving his mind without joy. Recognizing his limitation, he brought this doubt to Sai Baba. Baba's guidance was not a direct explanation but a prophecy: he told Das Ganu that "The resolution of this doubt of yours will be done by the maidservant at Kaka’s house" upon his return.