According to Chapter 20, what specific difficulty did Das Ganu encounter with the Ishavasya Upanishad, and what was Sai Baba's surprising instruction to resolve it?

In Chapter 20 of the Sai Satcharitra, the specific problem faced by Das Ganu was related to his work on a commentary called 'Ishavasya-Bhavartha-Bodhini.' Although he had translated the Upanishad word for word into simple language, he found no satisfaction because he could not comprehend its 'internal secret' or deep, hidden meaning. Troubled by this doubt, he went to Shirdi to seek guidance from the Satguru. Sai Baba's instruction was highly unconventional. Instead of providing a direct philosophical explanation, Baba told him, 'The resolution of this doubt of yours will be done by the maidservant at Kaka’s house when you return there.' This surprising response highlights Baba's unique teaching methods and the principle that divine insight can be delivered through unexpected channels via the Guru's grace.