What was the specific problem Das Ganu was facing with the Ishavasya Upanishad, and how did Sai Baba initially respond in Shirdi?

According to Chapter 20, Das Ganu was creating a commentary called the "Ishavasya-Bhavartha-Bodhini" to explain the scripture in simple language. Although he completed a word-for-word translation, he felt no joy because he could not grasp the deep internal meaning or "internal secret" of the Upanishad. Feeling stuck, he took this doubt to Sai Baba in Shirdi. Baba's initial response, as recorded in Chapter 20, was quite mysterious. He told Das Ganu, "The resolution of this doubt of yours will be done by the maidservant at Kaka’s house When you return there," setting up the next part of the story.