What problem was Das Ganu facing with the Ishavasya Upanishad, and what did Baba tell him about it?

Das Ganu was working on a commentary called the "Ishavasya-Bhavartha-Bodhini" to explain the deep meanings of the Ishavasya Upanishad in simple Prakrit language for those unfamiliar with Sanskrit. As Chapter 20 explains, although he could translate the scripture word for word, he felt he could not grasp its internal secret, and his mind found no joy in the work. When he took this doubt to Sai Baba in Shirdi, Baba did not explain it himself. Instead, 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."