What problem did Das Ganu face while working on the Ishavasya Upanishad, and what was Sai Baba's unusual instruction to him?

According to Chapter 20 of the Sai Satcharitra, Das Ganu was working on a commentary called the 'Ishavasya-Bhavartha-Bodhini' to explain the Upanishad in simple Prakrit language. Although he translated the text word for word, he struggled because he could not grasp its deep 'internal secret,' which left his mind without joy. When he took this doubt to Sai Baba in Shirdi, Baba gave him a surprising instruction. Instead of explaining it himself, Baba told him, 'The resolution of this doubt of yours will be done by the maidservant at Kaka’s house when you return there.'