Why did the Muslim League first accept and then reject the Cabinet Mission proposals?

The Muslim League accepted the Cabinet Plan in its entirety on June 6, 1946 because it felt that the grouping of Muslim-majority Provinces in a way meant the formation of Pakistan.

However, when the elections for the Constituent Assembly were held in July 1946, the Congress won 201 seats out of 292 seats which were reserved for the British India. It gained comfortable majority in the Assembly. The Muslim League could secure only 73 seats and felt disappointed. It demanded the establishment of two different Constituent Assemblies. The Muslim League under Jinnah's leadership passed a resolution on July 29, 1946 and rejected the Cabinet Mission Plan.